AWUS01 KWNH 141834
FFGMPD
SDZ000-NDZ000-150000-

Mesoscale Precipitation Discussion 1085
NWS Weather Prediction Center College Park MD
233 PM EDT Sun Sep 14 2025

Areas affected...central North Dakota

Concerning...Heavy rainfall...Flash flooding possible

Valid 141830Z - 150000Z

Summary...Localized rainfall totals as high as 3-4" in 2-3 hours
may result in isolated instances of flash flooding.

Discussion...A mid-upper level shortwave trough lifting north
across the Central High Plains is driving the organization of deep
convection over north-central SD early this afternoon, as a
strengthening area of low-level (concentrated at 850 mb) moisture
flux transport becomes better aligned with the right-entrance
region of a ~100 kt jet streak centered near eastern MT into
Saskatchewan, Canada. While lapse rates are unimpressive overall
(solidly moist adiabatic throughout the low to mid-level profile),
MUCAPE of 250-500 J/kg has been sufficient with aforementioned
strong dynamics to result in efficient 1-3"/hr rainfall
accumulations (with PWs of 1.5-1.7" near record territory for
mid-Sep, closer to the max moving average of the climatological
peak during late July and early August).

Localized south-to-north training of convection within the=20
meridional flow regime will likely result in additional 2-3"
totals, and may locally exceed 3" (per 12z HREF neighborhood
probabilities of 20-40%). While USGS streamflows in the region are
generally indicated to be above normal, tributaries of the
Missouri River are well below flood stage. Therefore any isolated
instances of flash flooding should be confined to particularly
vulnerable low-lying areas (with urbanized surfaces quite limited
in this rural area) that receive as much as 3-4" of rainfall in
2-3 hours.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-fCmDq4-APeJaEJlYRovtuTiLtGng8VvbtMLV4QfcLUK6G5NtFU72e6wosk17mLahEtj= Lr2OIBWSgsKcEj5MdzhkIhg$ for graphic product...

ATTN...WFO...ABR...BIS...FGF...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 49180048 49049938 47719957 46589979 45749999=20
45440074 45750148 46950168 47760162 48730160=20
49120120=20

=3D =3D =3D
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AWUS01 KWNH 142126
FFGMPD
KSZ000-NEZ000-150200-

Mesoscale Precipitation Discussion 1086
NWS Weather Prediction Center College Park MD
526 PM EDT Sun Sep 14 2025

Areas affected...South-Central Nebraska...Adj Northwest Kansas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 142130Z - 150200Z

SUMMARY...Very slow moving thunderstorms capable of 1.5"/hr with
possible short-term mergers up to 2"/hr locally may result in
scattered 2-4" totals over the next few hours before eventual
increased propagation eastward.

DISCUSSION...GOES-E WV suite shows core of mid-level closed low
over the southern Sand Hills of Nebraska, with a smaller scale
vorticity center rotating around the northern into the northwest
quadrant of the larger parent. This has sharpened the southern
base of the larger scale center, allowing for early afternoon
clearing to enhanced insolation and increase broader pool of
unstable air with narrow pool of 2000 J/kg CAPE be maintained
across south-central Nebraska, along and east of the slow moving
frontal zone. With bulk of stronger mid-level forcing and solid
eastern side meridional jet, the unstable air south of the Sand
Hills still has sufficient moisture angled back toward a weak
surface inflection near McCook. Tds in the mid 60s and total PWat
values of 1.25 to 1.4" fluxed on slightly backed surface to
boundary layer flow has maintained solid deep layer moisture flux
convergence for isolated cells (southwest Custer county over the
last few hours) to start increasing in coverage, expanding into
far northwest KS. Hourly rates of 1.5"/hr are likely and with
very slow cell motions nearly directly under the steering flow
axis, shows only very slow eastward propagation over the next few
hours. As such, localized totals of 2-4" are becoming more
probable, given slow motions and remaining instability/moisture
pool downstream.=20=20

Limiting factor toward flash flooding is, typical of the region,
soil conditions being near the Sand Hills. However, lower FFG
south of the main Hills region through the Platte River Valley and
across into N KS are 1.5"/hr and generally 2-2.5"/3hrs; given area
is in prolonged drought with 0-40 cm soil saturation ratios below
10%, the top portions may have become a bit more hydrophobic, and
given intensity of rates, may result in increased runoff and
possible incidents of localized flash flooding.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8_b5T0SXqTS89SLz4voo1SPwFglBjbJ3oDM0DNN0FtBhAwfsXU4v67guPn3hTcr_BhZo= b8LHzZCmWIdTm_6KCMzV5IY$ for graphic product...

ATTN...WFO...GID...GLD...LBF...

ATTN...RFC...KRF...NWC...

LAT...LON 41859888 41659855 40579862 39569922 39420057=20
40000109 40710098 41180063 41390032 41779966=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 150348
FFGMPD
TXZ000-OKZ000-150715-

Mesoscale Precipitation Discussion 1087
NWS Weather Prediction Center College Park MD
1147 PM EDT Sun Sep 14 2025

Areas affected...TX Panhandle into western OK

Concerning...Heavy rainfall...Flash flooding possible

Valid 150345Z - 150715Z

Summary...Brief training of thunderstorms may result in 2+ inches
of rain in an hour or less along with isolated flash flooding
across the TX Panhandle and possibly into western OK. The threat
Is expected to persist for at least a couple more hours.

Discussion...KAMA reflectivity at 0330Z showed a small area of
thunderstorms over the northeastern TX Panhandle into far western
OK, drifting south but also backbuilding toward the west. The
storms formed along a weak, retreating dryline which has moved
westward to near Cannon AFD as of 03Z. A southward sinking
boundary was evident via surface observations and reflectivity
data, a combination of outflow and a weak cold front which has
pressed south of Dalhart and Dumas since 00Z. Meanwhile, southerly
850 mb winds were increasing across West TX with RAP forecasts
indicating speeds near 30 kt by 06Z.

Given MLCAPE of roughly 1000-2000 J/kg over the Panhandle (00Z AMA
sounding and SPC mesoanalysis) and relatively weak CIN which
should continue to be overcome by overrunning of the southward
sinking psuedo-cold front, thunderstorms are expected to persist
for another couple of hours. Periods of backbuilding are likely to
continue and with mean westerly flow aloft, some training could
result. Earlier rainfall measurements over the northeastern TX
Panhandle showed ~0.75 inches of rain in 15 minutes, which could
result in 2+ inches of rain in an hour or less should training
persist long enough over a given location. The flash flood threat
should remain isolated in nature but also persist for an
additional 2-4 hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-7EI611l50GQRgfoignEVvvvS4WIk2IVD_VSEJ9nlW9qskEN8A8UNRQ8OWXeA1EjMwfm= rhNd9VpoGNlnXbdzr8gBrD4$ for graphic product...

ATTN...WFO...AMA...OUN...

ATTN...RFC...TUA...NWC...

LAT...LON 36129985 35669969 35229988 35030039 34900123=20
35140190 35670199 36080140 36100054=20

=3D =3D =3D
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AWUS01 KWNH 150550
FFGMPD
SDZ000-NDZ000-151145-

Mesoscale Precipitation Discussion 1088
NWS Weather Prediction Center College Park MD
149 AM EDT Mon Sep 15 2025

Areas affected...central to western ND

Concerning...Heavy rainfall...Flash flooding possible

Valid 150547Z - 151145Z

SUMMARY...Slow moving showers and thunderstorms will pose an
isolated risk for flash flooding for central and western ND
through 12Z. Hourly rainfall of 1 to 2 inches is expected along
with 2 to 4 inch storm totals.

DISCUSSION...GOES-E WV suite showed a NW to SE elongated mid-level
low centered over western SD at 0530Z, slowly lifting north, with
embedded smaller scale vorticity maxima. These vorticity maxima
were contributing to widely scattered showers and thunderstorms
from the ND/SD border into western ND. The environment across the
western half of ND was characterized by a small pocket of 500-1000
J/kg MLCAPE and 1.3 to 1.6 inch PWATs (90-95th percentile) via 05Z
SPC mesoanalysis data. MUCAPE values were slightly higher with low
LPL levels below 750m AGL.

As the closed low moves north over the next 3-6 hours, a
combination of slightly colder 500 mb temperatures (locally
increased instability) and associated vorticity maxima are
expected to lead to development of additional showers and
thunderstorms over west-central ND. Deep layer mean winds beneath
the closed low were fairly weak at 10 kt or less, which will
support slow moving cores of heavy rain, with the expected
coverage of slow moving cores peaking over the next 2-5 hours. The
anomalously moist environment and slow moving cores of heavy rain
should lead to hourly rainfall of 1 to 2 inches along with spotty
2-4 inch storm totals. These localized heavy rainfall areas may
lead to isolated flash flooding through 12Z considering 3-hr FFG
values below 2 inches in many locations.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8JvCWaV2gr9UM0b8XuReM0k0df62_TYCVZ6XJmm9C7plvOYDRWV4LMy0VRNbnWpU7ICj= 7xUBtSSW-bRr-8LwXuO11Y0$ for graphic product...

ATTN...WFO...ABR...BIS...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 49110183 49000131 48470118 47820084 46980035=20
46380031 46000082 45870163 46100259 46740342=20
47770369 48830356 49050295 49070234=20

=3D =3D =3D
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AWUS01 KWNH 152032
FFGMPD
MOZ000-ARZ000-160100-

Mesoscale Precipitation Discussion 1089
NWS Weather Prediction Center College Park MD
431 PM EDT Mon Sep 15 2025

Areas affected...North to South Central Missouri...Far
north-central Arkansas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 152030Z - 160100Z

SUMMARY...Band of slow moving pulse-like convection with
1.5-1.75"/hr and widely scattered localized totals to 2"+ in 1-3
hours. Localized flash flooding and low-water crossing issues are
possible through evening.

DISCUSSION...A narrow ribbon of enhanced moisture and low-level
theta-E is being squeezed by oblique passing of very broad/strong
upper-level trough over much of the Northwest CONUS and return
flow under the closed ridge over the Great Lakes. This ribbon of
1.5-1.75" extends along the Upper Mississippi River through MO
into central Arkansas. Solid surface heating with temperatures
into the low 90s over mid 60s Tds supported fairly unstable
environment with 2000-2500 J/kg of MLCAPE along the eastern/upwind
edge of the deeper moisture plume.=20

The deeper layer confluence, along with weakened cap resulted in
initial thunderstorms, though recent uptick has been noted over a
much longer length of the instability/moisture axis. Strong
updrafts with numerous overshooting tops dotting the length of the
convective line, from Shelby to Osage to Texas and to Howell
county in MO, becoming more scattered further south where
mid-level convergence is slightly reduced (nose of return flow
across south-central MO).

Very oblique right entrance divergence and subtle 20kt effective
bulk shear may allow for some vertical disconnect to the
up/downdraft couplets to support a few updraft cycles, though
overall organization is fairly weak and cell longevity is likely
to be limited to 1-2 hours. However, vertical loading to the
downdraft and very slow cell motions may allow for rates of
1.5-1.75"/hr and may result in widely scattered 2"+ totals in less
than 2hrs. Overall, the grounds are quite dry with 0-40cm
relative soil moisture at or below 30%, so while FFG values are
very high, they may be discounting the initial harder/impermeable
nature before eventual infiltration occurs, and given the sheer
rate, the initial runoff may be higher than expected, resulting in
widely scattered flash flooding conditions, especially near
low-water crossings that dot the area and therefore is considered
possible over the next 3-4 hours.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5sLA42kk-nHBN0tFeRaAJbC4enJwgUEj0QCsqbVwwwsomzGDpA_wJQwe1ASN8uoMj4hn= BZpxv0YGVUH7RBYlY2rnthM$ for graphic product...

ATTN...WFO...EAX...LSX...LZK...SGF...

ATTN...RFC...KRF...MSR...ORN...NWC...

LAT...LON 40379249 39809183 39149162 37979136 37299133=20
36429134 36109214 36389272 36909316 38189353=20
39829328 40369283=20

=3D =3D =3D
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AWUS01 KWNH 160833
FFGMPD
VAZ000-NCZ000-161400-

Mesoscale Precipitation Discussion 1090
NWS Weather Prediction Center College Park MD
432 AM EDT Tue Sep 16 2025

Areas affected...coastal southeastern VA and northeastern NC

Concerning...Heavy rainfall...Flash flooding possible

Valid 160831Z - 161400Z

Summary...At least a localized flash flood threat looks to be
increasing across coastal sections of southeastern VA and
northeastern NC this morning. Increasing rainfall rates with
hourly totals potentially reaching 3 inches are expected to impact
a few coastal locations through 14Z.

Discussion...08Z surface observations and shortwave IR imagery
from GOES East showed a surface low centered about 65 miles east
of Cape Hatteras. Over the past 6 hours, the surface low has been
gradually lifting north to northwest while occasional mesoscale
lows have appeared in the broader low level cloud swirl in
satellite imagery. It appears the main surface low has been
associated with the most recent burst of convection to its
northwest, with area radar imagery showing reflectivity echoes
crossing over Hatteras Island. SPC mesoanalysis data from 08Z
showed the convective burst along the western edge of a MLCAPE
bubble offshore within 1000-2000 J/kg, just east of the northern
Outer Banks. Meanwhile, moderate to occasionally heavy rain has
been observed over VA, to the southwest of Norfolk, with 1-2
inches reported since midnight. However, a lack of better
instability has limited rainfall intensity for inland locations.

Short term RAP guidance over the past 6-10 cycles has been in
relatively good agreement with the current surface low position
and supports the low tracking toward the northwest, closer to the
Outer Banks, through 14Z. This movement makes sense given the
low's placement relative to a closed mid-level low centered over
the central NC/SC border. Even if the RAP is wrong, there is the
potential for convectively induced mesovortices within convection
that may reach the coast before dissipating. An expected
northwestward movement of the surface low should support
increasing MLCAPE from roughly Cape Hatteras to Virginia Beach
with values of 500 J/kg to the north and up to ~1500 J/kg over
Hatteras Island by 12-14Z. In addition, a primary axis of low
level convergence to the northwest of the low center is expected
to make it to the northeastern NC and southeastern VA coast with
increasing rainfall intensities beneath favorably diffluent flow
in the upper levels. Additional, weaker and more transient axes of
low level convergence will be possible farther inland from the
coast which could support increased rainfall intensities as
instability increases later this morning.

Earlier gauge observations had shown ~0.75 inches of rain in 15
minutes which would support hourly rainfall up to 3 inches.
Expected hourly rainfall of 1 to 3 inches will be possible from
portions of northeastern NC into southeastern VA which may result
in localized flash flooding, especially over any urban locations.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_qFJKYsDtL4cZcV9URN8n6DzfJPHVrjrdZ4SrWpKuYZJT3MpZOotEOBGA3Yh_Nh-nYXj= iy_iNscaFNoTEa2lzNuZGzE$ for graphic product...

ATTN...WFO...AKQ...MHX...RAH...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 37197676 37137627 36787569 35957506 35177532=20
35167600 35567677 36077735 36497755 37067729=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 161401
FFGMPD
VAZ000-NCZ000-162000-

Mesoscale Precipitation Discussion 1091
NWS Weather Prediction Center College Park MD
1001 AM EDT Tue Sep 16 2025

Areas affected...Southeast VA and far Northeast NC Tidewater
Region

Concerning...Heavy rainfall...Flash flooding likely

Valid 161400Z - 162000Z

SUMMARY...Ongoing heavy rainfall across parts of southeast VA and
far northeast NC associated with a potent nearby coastal low is
expected to continue through at least this afternoon. Maximum
rainfall rates are expected to remain in the 1-3"/hr range, with
6-hr totals up to 4". This is anticipated to lead to scattered
instances of flash flooding, which may be exacerbated due to
coastal flooding impacts and urbanized ground conditions.

DISCUSSION...Latest GOES-EAST visible satellite imagery highlights
a compact surface low pressure system about 40 miles east of the
NC Outer Banks, with regional radar imagery and surface
observations depicting moderate to locally heavy rainfall across
coastal sections of VA and far northeast NC. Rainfall amounts
through 1330Z of 1.5-2.0" have been reported in the
Norfolk/Virginia Beach region, mainly associated with a band of
heavy rainfall that moved westward through the region this
morning. The highest rainfall rates (up to 3"/hr per MRMS) are
currently offshore and associated with the deepest convection
(coldest cloud tops around -66C) near the low pressure center.
However, an axis of low-level convergence extends to the northwest
along the VA/NC coastline and enhanced by 30-40kt
east-northeasterly 850mb winds and an associated warm front
extending east-northeast from the low pressure system. This strong
easterly flow, while enhancing convergence, is also maybe more
importantly aiding to increase MUCAPE above 500 J/kg per the
latest RAP into northeast NC. Elevated instability is expected to
continue increasing gradually through this afternoon as the
surface low slowly drifts north-northwestward, as well as PWs
which should remain near or slightly below 2". This will help
maintain rainfall rates in the 1-3"/hr range and eventually lead
to greater coverage of these higher rates through around 20Z as
additional rainbands move inland.

Radar representations over the next 6-hrs will likely exhibit
north-south bands of heavy rainfall moving inland along the coast
where greatest convergence exists intersecting the coastline and
influence from an associated warm front and easterly flow. These
bands will likely weaken as they progress westward, before being
replaced by new heavy rainfall bands oriented in a similar fashion
as the coastal low drifts closer to southeast VA. Latest HRRR and
experimental RRFS guidance depicts additional rainfall amounts up
to 4" possible through 20Z and most likely along the immediate
coast of southeast VA and the southern Delmarva Peninsula, but
with even heavier amounts possible just after 20Z. These rainfall
amounts when combined with coastal flooding and any urban
influence (i.e. Norfolk/Virginia Beach) are likely to lead to
scattered instances of flash flooding during this time period.
Additional MPDs will likely be needed this evening as the event
continues through tonight.

Snell

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7gTRZCSpog-C5MyufQ3TDTH0pwcX6tkmHt6QpYZ-K42h1LT0wga_hPz_SMhsMBkuRAWo= YTDU5dTV9Z0iIvN7unyfh3M$ for graphic product...

ATTN...WFO...AKQ...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 37727599 37647566 37447549 37257559 36887571=20
36457573 36377601 36707647 37107668 37427662=20
37647633=20

=3D =3D =3D
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AWUS01 KWNH 161845
FFGMPD
TXZ000-NMZ000-AZZ000-170045-

Mesoscale Precipitation Discussion 1092
NWS Weather Prediction Center College Park MD
245 PM EDT Tue Sep 16 2025

Areas affected...Southeast Arizona into southwest/central New
Mexico

Concerning...Heavy rainfall...Flash flooding possible

Valid 161845Z - 170045Z

SUMMARY...Scattered slow moving convection initiating this
afternoon will contain the potential for localized rainfall rates
of 1.0-1.5"/hr between southeast Arizona and southwest/central New
Mexico. This may lead to isolated flash flooding, especially near
burn scars and dry washes.

DISCUSSION...Satellite and regional radar imagery across
east-central AZ into central NM highlight ongoing convection
blossoming over the last hour within an unstable environment (RAP
analysis of 1,000-1,500 J/kg SBCAPE). PWs are not anomalous and
remain under 1" outside of southern AZ/NM. The greatest factor
increasing the flash flood risk, when combined with the sufficient
instability levels, are weak mean layer westerly winds around
10-15kts. This may allow for convection tied to sensitive terrain
to remain mostly stationary for enough time with rainfall rates up
to 1.0-1.5" and lead to isolated flash flooding. Additionally,
some west-east training of cells are possible across central NM
through this evening should convection align in this orientation.

This flash flood risk, while isolated, is greatest near recent
burn scars and dry washes. Considerable flash flooding is possible
should thunderstorms directly impact the most sensitive terrain in
the region.

Snell

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8PQg8iv6qvvbFsEnsBA24u0eBzMBhSYKFBVaX0HGZ2cmSNPz1PXQvzj9fT_shMhnhr2K= wMclO_hpKeRbLd_W0B3DkEk$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 35040588 34870514 34360493 33030512 32140560=20
31790645 32140746 31960886 31271054 31271139=20
31651184 32621074 33310997 34190975 34420855=20
34860707=20

=3D =3D =3D
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AWUS01 KWNH 161855
FFGMPD
MOZ000-IAZ000-KSZ000-NEZ000-162253-

Mesoscale Precipitation Discussion 1093
NWS Weather Prediction Center College Park MD
254 PM EDT Tue Sep 16 2025

Areas affected...Iowa, northwestern Missouri, far northeastern
Kansas

Concerning...Heavy rainfall...Flash flooding possible

Valid 161853Z - 162253Z

Summary...Isolated to scattered thunderstorm activity was
developing and moving slowly across the discussion area. Local
rain rates reaching 2 inches/hr are possible in a few spots,
potentially causing isolated flash flooding.

Discussion...Radar/satellite imagery depicts developing
thunderstorms across central Iowa generally along an axis from
near Mason City south-southwestward to west of Des Moines. More
isolated convective activity was attempting to deepen into far
northeastern Kansas. Strong insolation/surface destabilization
has enabled deeper convection to become sustained along a subtle
surface confluence in that vicinity. Meanwhile, PW values
exceeding 1.5 inch and minimal convective inhibition is
contributing to efficient rainfall processes, with local 1-1.5
inch/hr rain rates already noted west of Des Moines. Both forcing
aloft and kinematics were weak, resulting in slow-moving activity
that should persist for a few hours this afternoon.

The longevity of ongoing activity (and extent of flash flood risk)
should generally be tied to the persistence of subtle low-level
confluence across the region today. Models suggest that storms
should persist for at least another 3-5 hours or so. Ground
conditions are a bit on the dry side (modest soil moistures per
NASA SPoRT data) and relatively high FFG thresholds (around 2
inches/hr). Each of these factors, plus questions about the
spatial extent of convective coverage through 23Z/6p CDT) are all
suggestive of an isolated flash flood threat at best.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6FCF-YyOcArnRO2MP5B6HBflcxen68JbVGfYG0zACTfGyMQyVm-vi6C6zxAMqS5Pvi1k= mKv5t1ZU4stxMH2UJcMCDpU$ for graphic product...

ATTN...WFO...DMX...EAX...OAX...TOP...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 43259428 43209326 41879333 40659384 39569404=20
39419477 39829600 42129526=20

=3D =3D =3D
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AWUS01 KWNH 161935
FFGMPD
DEZ000-MDZ000-VAZ000-170134-

Mesoscale Precipitation Discussion 1094
NWS Weather Prediction Center College Park MD
334 PM EDT Tue Sep 16 2025

Areas affected...southeastern Virginia, southeastern Maryland, far
southern Delaware

Concerning...Heavy rainfall...Flash flooding likely

Valid 161934Z - 170134Z

Summary...Flash flood potential continues across the discussion
area. Heavy rainfall will continue around the center of a
westward-moving low pressure area near the southeastern VA coast
over the next 6 hours.

Discussion...Flash flood potential continues across southeastern
Virginia. Heavy rainfall continues near the center of a coastal
low (centered just east of Virginia Beach). That low was moving
slowly westward toward mainland Virginia while spreading areas of
0.5-2 inch/hr rain rates into the discussion area. Some of these
heavier rain rates will spread over areas that have already
experienced 2-4 inch totals today. Flood/flash flood impacts have
already been noted near Norfolk and Virginia Beach. Impending
rainfall (perhaps reaching 2-3 inches in spots) should exacerbate
any flooding conditions in the area and cause new instances of
flash flooding through at least 23Z/7p EDT.

An addition to the aforementioned scenario, a deep convective band
has materialized over coastal waters southeast of
Salisbury/Pocomoke City, MD on the northeastern periphery of the
coastal low. The amount of lightning associated with this
activity suggests that mesoanalyses may not be accurately
depicting instability profiles in that region. Surface-based
instability is expected to make it to shore and support
persistence of this band across southeastern Maryland and adjacent
parts of Virginia, with rain rates exceeding 1 inch/hr for a few
hours. Excessive rainfall/flash flood potential will also
accompany this activity through 02Z/10p EDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_3G9l2zeNRO6vY7onx6yFLgGMxhJrN7BmxQ61N_fOUf5-IqClfbv5nKCSANUXNygqHOn= 0VLHiSo1wZKqd3Hesg_XfZs$ for graphic product...

ATTN...WFO...AKQ...LWX...PHI...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 38597577 38527504 37657525 36597588 36727724=20
37697698=20

=3D =3D =3D
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AWUS01 KWNH 162118
FFGMPD
KSZ000-NEZ000-COZ000-170317-

Mesoscale Precipitation Discussion 1095
NWS Weather Prediction Center College Park MD
518 PM EDT Tue Sep 16 2025

Areas affected...southwestern Nebraska, northwestern Kansas

Concerning...Heavy rainfall...Flash flooding possible

Valid 162117Z - 170317Z

Summary...Slow-moving convection continues to deepen across the
discussion area, with areas of 1+ inch/hr rates noted beneath the
strongest storms. Areas of flash flooding are possible through
03Z/10p CDT.

Discussion...Scattered thunderstorms were increasing in coverage
across the discussion area over the past hour. The storms appear
to be focused along low-level convergence near an apparent weak
boundary (wind fields shifting from southerly to easterly along an
axis from near Holyoke, CO to near Hebron, NE. Along this
boundary, 1-1.2 inch PW values, 2000+ J/kg MLCAPE, and steep lapse
rates aloft were allowing for intense updrafts and locally heavy
rainfall. Most storms were drifting northward amid modest deep
layer flow, although a cell near McCook, NE has anchored along
this boundary and slowed substantially while exhibiting
backbuilding character. Rain rates appear to be at a peak near
this storm (exceeding 1.5 inch/hr), and it cannot be ruled out
that other storms exhibit this same behavior in the short term.

Storms appear to be aided by ascent aloft associated with a weak
mid-levels shortwave trough evident in water vapor imagery over
northeastern Colorado. This wave will take several hours to
traverse the region, and ascent from this feature should continue
interacting with the strong instability in place to keep fostering
deep convective development. Southerly 850mb flow into the area
should continue to maintain the pool of instability. Scattered,
slow-moving storms are expected to continue through at least
03Z/10p CDT this evening across the region. Local rain rates
exceeding 1.5 inches/hr should readily exceed FFG thresholds.=20
Flash flooding is probable on at least an isolated basis.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5FSQXGqhLMX1uVRBLlZ4oYfAXAnTmE3HW3X65HnkGI2ywM_kfZPqz0VBj79Hdk-0DDHd= HVOmXjRjrNaTme03JwTHu7I$ for graphic product...

ATTN...WFO...BOU...DDC...GID...GLD...ICT...LBF...

ATTN...RFC...KRF...NWC...

LAT...LON 41370236 40999943 39999801 38879816 39580196=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 162121
FFGMPD
KSZ000-NEZ000-COZ000-170317-

Mesoscale Precipitation Discussion 1095
NWS Weather Prediction Center College Park MD
521 PM EDT Tue Sep 16 2025

Areas affected...southwestern Nebraska, northwestern Kansas

Concerning...Heavy rainfall...Flash flooding possible

Valid 162117Z - 170317Z

Summary...Slow-moving convection continues to deepen across the
discussion area, with areas of 1+ inch/hr rates noted beneath the
strongest storms. Areas of flash flooding are possible through
03Z/10p CDT.

Discussion...Scattered thunderstorms were increasing in coverage
across the discussion area over the past hour. The storms appear
to be focused along low-level convergence near an apparent weak
boundary (wind fields shifting from southerly to easterly along an
axis from near Holyoke, CO to near Hebron, NE. Along this
boundary, 1-1.2 inch PW values, 2000+ J/kg MLCAPE, and steep lapse
rates aloft were allowing for intense updrafts and locally heavy
rainfall. Most storms were drifting northward amid modest deep
layer flow, although a cell near McCook, NE has anchored along
this boundary and slowed substantially. Rain rates appear to be
at a peak near this storm (exceeding 1.5 inch/hr), and it cannot
be ruled out that other storms exhibit this same behavior in the
short term.

Storms appear to be aided by ascent aloft associated with a weak
mid-levels shortwave trough evident in water vapor imagery over
northeastern Colorado. This wave will take several hours to
traverse the region, and ascent from this feature should continue
interacting with the strong instability in place to keep fostering
deep convective development. Southerly 850mb flow into the area
should continue to maintain the pool of instability. Scattered,
slow-moving storms are expected to continue through at least
03Z/10p CDT this evening across the region. Local rain rates
exceeding 1.5 inches/hr should readily exceed FFG thresholds.=20
Flash flooding is probable on at least an isolated basis.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4jmi6-Km_tH2OSDdTYFMa-kPDpy9lp1iuYSZIfeFlCsbinrPGu9HfxOBM43lS8NPCTsn= ZCIu9LpzWoZSH2_y_KkSZM0$ for graphic product...

ATTN...WFO...BOU...DDC...GID...GLD...ICT...LBF...

ATTN...RFC...KRF...NWC...

LAT...LON 41370236 40999943 39999801 38879816 39580196=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 170111
FFGMPD
NMZ000-AZZ000-170510-

Mesoscale Precipitation Discussion 1096
NWS Weather Prediction Center College Park MD
911 PM EDT Tue Sep 16 2025

Areas affected...southern New Mexico, southeastern Arizona

Concerning...Heavy rainfall...Flash flooding possible

Valid 170110Z - 170510Z

Summary...Flash flood potential will exist on an isolated basis
for a few more hours - perhaps through 05Z/11p MDT.

Discussion...Scattered storms have developed in earnest and moved
slowly across the discussion area this afternoon. As of 01Z,
radar mosaic imagery indicates the heaviest thunderstorm activity
located across southern New Mexico from near Silver City to near
Alamogordo, with more isolated activity noted near Tuscon.=20
Surface-based CAPE remains in place in the pre-convective
environment (ranging from 500-1000 J/kg) and PW values remain
around 1-1.2 inch. Additionally, steering flow/kinematics
continue to favor slow- and erratically moving storms, with
perhaps a very slow southward component of propagation noted
across south-central New Mexico. Spots of 1 inch/hr rain rates
will continue to threaten local FFG and pose a risk of flash
flooding in localized areas.

The extent of the flash flood threat should continue for another
2-3 hours or so. The loss of daytime heating and continued
overturning should allow for a lessening of both convective
intensity and coverage through the early overnight hours.=20
Isolated flash flooding remains possible through 05Z/11p MDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9VnATxD6wneBFkKlJbs0pC2m79OBrH2VN4o4ue6HJV89321kNuz5Z_yIV4Yo2s3FG98O= oTE0w2TVW52covsJO7I7Lsg$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...MAF...PSR...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 33950560 32630478 31970675 31360842 31651198=20
32151226 33651008=20

=3D =3D =3D
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AWUS01 KWNH 170325
FFGMPD
IAZ000-KSZ000-NEZ000-170810-

Mesoscale Precipitation Discussion 1097
NWS Weather Prediction Center College Park MD
1125 PM EDT Tue Sep 16 2025

Areas affected...northern KS into central/eastern NE

Concerning...Heavy rainfall...Flash flooding possible

Valid 170324Z - 170810Z

Summary...A few areas of flash flooding will continue to be
possible from northern KS into central/eastern NE through 08Z. 1-2
in/hr rates within training are expected.

Discussion...03Z radar imagery showed ongoing thunderstorms along
the western KS/NE border into east-central NE, located southeast
of a stationary front that extended NE to SW through central NE.
An outflow boundary was analyzed ahead of the thunderstorms with
overrunning of an estimated 30-40 kt 850 mb low level jet in
west-central KS beneath a diffluent flow pattern aloft. The bigger
picture showed a closed mid to upper level low over WY with a
southward extending trough axis into western CO. This trough axis
is expected to advance eastward over the next 6 hours with
diffluent flow maintaining over much of NE into northern KS.

Areas of strong ascent will continue over the next several hours
across the central Plains with lingering instability of 1000-2000
J/kg MLCAPE aiding in the maintenance of thunderstorms with high
rainfall rates. As the outflow boundary continues to advance
downstream toward the south and east, overrunning of the low level
jet atop the boundary with deeper layer mean steering flow
aligning with the boundary orientation will support areas of
training at times from SW to NE. Rainfall rates of 1-2 in/hr are
expected with additional storm totals of 2-4 inches through 08Z
which may allow for a few areas of flash flooding from northern KS
into central and eastern NE.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4vEcU5WwLldfJTdEHUbPwTFoIITQFfuXx8YiqwQ30tDiN3tcMrsg3xf-OOX5VuQ0VZio= -JA9pwNJq-LVVTtTh6ntgoo$ for graphic product...

ATTN...WFO...FSD...GID...GLD...ICT...LBF...OAX...TOP...

ATTN...RFC...KRF...NWC...

LAT...LON 42569757 42419687 42159630 41819610 41499628=20
40939691 40089751 39199818 39270019 39600094=20
39890116 40890035 41489958 42089867=20

=3D =3D =3D
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AWUS01 KWNH 170351
FFGMPD
IAZ000-NEZ000-170700-

Mesoscale Precipitation Discussion 1098
NWS Weather Prediction Center College Park MD
1150 PM EDT Tue Sep 16 2025

Areas affected...western/central IA

Concerning...Heavy rainfall...Flash flooding possible

Valid 170349Z - 170700Z

SUMMARY...A few slow moving thunderstorms will continue at least a
localized flash flood threat over western IA over the next few
hours with hourly rainfall of 1 to 2+ inches.

DISCUSSION...GOES East infrared imagery was continuing to show
cooling cloud tops over the past 30-45 minutes over western IA
where an outflow boundary was being overrun by a 10-20 kt low
level jet. Aloft, deeper layer mean wind speeds were weak,
supporting slow cell motions over IA with MRMS derived rainfall
rates of 1 to 2+ inches in an hour since 00Z. While the stronger
upper level forcing and low level jet magnitude were located to
the west across NE, a weaker branch of the low level jet extended
over eastern NE into western/central IA into the upper MS Valley,
proving sufficient for overrunning and scattered low moving storms
where MLCAPE ranged from 500-1500 J/kg via 03Z SPC mesoanalysis
data. Continued areas of slow moving thunderstorms will continue
at least a localized threat of flash flooding over the next 2-4
hours with increasing convective inhibition possibly lowering the
threat after 07Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_qaWfoF4k1_2qc5TOW7O4StwE49Ae9_97v_RYBCjEx16i3qswK5RMSCf9UWDli2oBd-n= 3HzGmDGx1rCE58mwutbqofc$ for graphic product...

ATTN...WFO...DMX...FSD...OAX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 43439448 43189370 42369300 41269400 40999576=20
41349626 42109652 42559627 43019587 43379520=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 180026
FFGMPD
MNZ000-SDZ000-180524-

Mesoscale Precipitation Discussion 1099
NWS Weather Prediction Center College Park MD
825 PM EDT Wed Sep 17 2025

Areas affected...eastern South Dakota, far western Minnesota

Concerning...Heavy rainfall...Flash flooding possible

Valid 180024Z - 180524Z

Summary...A fairly focused band of slow-moving convection is
producing rain rates exceeding 1.5 inches/hr. Areas of excessive
runoff and flash flooding are expected. This risk should persist
through around 05Z/midnight CDT.

Discussion...A fairly focused band of convection was pivoting
slowly westward on the eastern periphery of a surface low center
south of Pierre, SD. This band extended from just north of Huron,
SD eastward to just west of Marshall, MN. This band was also
collocated with focused low-level convergence and a stationary
front in the area. South of the front, areas of 500-1000 J/kg
SBCAPE and 1.5 inch PW values were promoting updrafts with
efficient rainfall processes. With convection slowly moving and
focused along the nearly stationary front, spots of 2 inch/hr rain
rates were being estimated per MRMS. These rain rates were
persisting in local areas for some time, likely causing at least
isolated runoff concerns.

Models generally depict that this scenario will not change much
over the next 3-5 hours. Instability south of the boundary will
only be slowly exhausted with boundary layer cooling. Spots of
1-2 inch/hr rain rates are likely to continue, and isolated areas
could experience total amounts of 3-5 inches over the next few
hours. Convection should only gradually weaken after 05Z or so.=20
Flash flooding is possible in a localized basis in this scenario.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_AlqbLxOJ3EYu3kmeAcfrfTm2Nb6SDNqDlb-bOUepbeMHIzPk6C-Xu_djkN0NFkB5aBL= PYfckMWEw00GGln7F4EhZUo$ for graphic product...

ATTN...WFO...ABR...FSD...MPX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 45229781 45229552 44589504 44109618 43799983=20
44939977=20

=3D =3D =3D
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AWUS01 KWNH 180157
FFGMPD
TXZ000-OKZ000-KSZ000-COZ000-NMZ000-180745-

Mesoscale Precipitation Discussion 1100
NWS Weather Prediction Center College Park MD
956 PM EDT Wed Sep 17 2025

Areas affected...Southeast CO...Far Northeast NM...Southwest
KS...OK Panhandle...Northern TX Panhandle...

Concerning...Heavy rainfall...Flash flooding possible

Valid 180155Z - 180745Z

SUMMARY...WAA band with some short-term training across TX
Panhandle to given way to upscale convective clusters out of SE
CO/NE NM. Scattered repeating through the overnight period may
present hourly rates/totals to 1.5" and localized 2-3 3-6 hour
totals downstream. Isolated incident or two of flash flooding is
considered possible.

DISCUSSION...GEOS-E WV suite shows a broad closed low over the
central High Plains though the inner core short wave/vorticity
features are fairly consolidated but showing a generally flat
elongated orientation across central CO toward the Sand Hills of
Nebraska. The upstream shortwave is sliding eastward with an
associated upper level speed max into a weakly diffluent region
across SW KS attm. As speed max rounds the base, this will expand
and overall divergence aloft will be favorable for upscale
convective growth toward the later portion of the period.=20

However, in the short-term term, scattered more severe-type
convection with solid hail generation exists across much of SE CO,
though organization suggests some random collision/mergers are
possible over the next few hours. More concerning is VWP and RAP
analysis suggests strengthening southerly to south-southwesterly
low level jet across the Texas Panhandle is responding to the
overall height-falls/ejection of the wave. A weak thermal
boundary from NNW to SSE is acting as the isentropic ascent fact
across far NE NM into the northern TX Panhandle. Here, WAA is
solid and MUCAPEs are near 2000 J/kg to support the elevated
convection. CIRA LPW also notes backed up moisture gradient from
afternoon upslope, combined with an axis of enhanced 850-700 to
.5" near this ascent plane, allowing for increasing moisture flux
into the currently severe/hail producing cells. Given total
moisture to 1.25" and increasing speed to 35kts, convergence
should support 1.5"+/hr rates.=20=20

Deep layer flow at the southern edge of the jet is support some
weak south-easterly motions for some scattered potential for
training/repeating elements. This may result in localized 2-3"
totals and possible flash flooding conditions over the next few
hours. With time, the strength and veering of the LLJ will
expand ascent across SE CO into SW KS into the aforementioned
expanding divergence field toward 06-07z. Forward propagation is
likely to limit overall coverage, but repeat tracks and expanding
clusters may also support localized 2-3" totals and isolated flash
flooding conditions through middle of overnight period.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9MXfjDXLe0g4EuNA_kspVcIBGmDFRnIA_hjcQzRmgqAhNjIiRQD-utosqBglXLfDCAsS= a9FJQ3jEiP6VKvF01Emqufk$ for graphic product...

ATTN...WFO...ABQ...AMA...DDC...GLD...OUN...PUB...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 38580228 38510076 38069976 36809946 35410016=20
35220225 35830347 37200421 38270358=20

=3D =3D =3D
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AWUS01 KWNH 181632
FFGMPD
AZZ000-NVZ000-CAZ000-182230-

Mesoscale Precipitation Discussion 1101
NWS Weather Prediction Center College Park MD
1231 PM EDT Thu Sep 18 2025

Areas affected...Southern and Eastern CA...West-Central to
Southwest AZ...Far Southern NV

Concerning...Heavy rainfall...Flash flooding likely

Valid 181630Z - 182230Z

SUMMARY...A gradual increase in the coverage and concentration of
showers and thunderstorms will be expected over the next several
hours. Increasingly heavy rainfall rates will pose a growing
threat for isolated to scattered areas of flash flooding by
mid-afternoon.

DISCUSSION...The early-day GOES-W visible satellite imagery along
with radar shows a broken axis of locally heavy showers and
thunderstorms impacting portions of eastern CA as a deep layer
fetch of tropical moisture/warm air advection and mid-level
shortwave energy related to former Tropical Storm Mario advances
up into the Southwest U.S.

Despite the current regional coverage of cloud cover, there will
be a gradual uptick in solar insolation across southeast CA and
into southwest AZ over the next several hours which is where
visible satellite imagery does show some thinning/clearing of the
cloud deck. This will drive an uptick in surface-based instability
over time, and with a well-defined instability gradient already in
place (SBCAPE values of 1000 to 2000+ J/kg) from the Gulf of CA
northward into the Lower CO River Valley, an increase in the
coverage of heavy shower and thunderstorm activity will be
expected.

Differential heating boundaries near areas of higher terrain and
also near the edge of the deeper layer cloud decks will be
facilitators of additional convective initiation. Additionally,
the flow aloft is rather divergent around the northeast flank of
the mid-level shortwave energy offshore of southern CA, and this
forcing interacting with the deeper layer southerly moisture/warm
air advection regime will also promote an increase in convective
coverage.

PWs are well into the 95th+ percentile of climatology across
southern and eastern CA in particular, with CIRA-ALPW showing substantial/highly anomalous concentrations of moisture in the
700/300 mb layer. This moisture coupled with the uptick in
surface-based instability should easily support convective cells
capable of producing 1 to 2 inch/hour rainfall rates by early to
mid-afternoon.

The latest 12Z HREF guidance suggests some localized backbuilding
and cell-training concerns, and the concentration of convection
will support rainfall totals by mid-afternoon of as much as 2 to 4
inches.

Isolated to scattered areas of flash flooding will become
increasingly likely with time given the high rainfall rates and
storm totals over the next several hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-dfCmWJ6CY2uuqTzuU-eee670QKSLFTWh2ApJ8Q9ixofl5V4_XFU_aHWvTI_InYcdTXh= XIBqvSTzKN_xCpJPU805pRE$ for graphic product...

ATTN...WFO...FGZ...HNX...LOX...PSR...SGX...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 36091632 36071540 35891429 35361298 34351203=20
33571209 33171309 32741382 32331443 32241510=20
32281583 32541653 33261700 34081727 35001829=20
35781806 36041724=20

=3D =3D =3D
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AWUS01 KWNH 181940
FFGMPD
TXZ000-NMZ000-AZZ000-190139-

Mesoscale Precipitation Discussion 1102
NWS Weather Prediction Center College Park MD
340 PM EDT Thu Sep 18 2025

Areas affected...southern New Mexico, southern/central Arizona,
far west Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 181939Z - 190139Z

Summary...Isolated thunderstorms are developing and moving
slowly/erratically across the discussion area. Peak rain rates of
around 1 inch/hr are likely with the most dominant storms.=20
Isolated instances of flash flooding are expected through 02Z/8p
MDT.

Discussion...Abundant insolation across the discussion area has
contributed to sufficient instability for convective development
this afternoon. Currently, thunderstorm initiation has occurred
mainly along terrain-favored ridgelines. Moisture profiles are
marginally supportive of heavy rainfall (around 0.9-1.1 inch -
highest in south-central Arizona), although recent radar
mosaic/MRMS depicts several spots of 1 inch/hr rain rates across
the discussion area. Kinematic profiles (containing weak steering
flow aloft) was allowing for cells to move slowly and even
erratically across the discussion area, further supporting very
localized areas of heavy rainfall. Some of these areas of heavier
rain were occurring over/near burn scars across southern New
Mexico, which could prompt a relatively fast increase of local
runoff in nearby flood-prone areas.

The ongoing scenario supporting flash flood potential should
continue for a few hours this afternoon as we're still early in
the diurnal heating cycle. Models depict scattered, slow-moving
convective activity to continue across the discussion area through
at least 02Z/8p MDT - perhaps lingering a bit longer across far
southern New Mexico and vicinity. Isolated instances of flash
flooding are expected during that timeframe.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_1tSnOKkfIHjlCIhn9STXdSvsc9DB7gSDvh4AGoDvHeQmoVG0MUalkGozrGi4L3jXukb= Y8xg43Fo1VJg7gB9rVaPNK0$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...MAF...PSR...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 35311239 35171158 34540949 34400828 34460678=20
33820522 31750449 30920424 30470440 30880520=20
31920667 31730823 31340824 31520986 31881128=20
33351258 34541279=20

=3D =3D =3D
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AWUS01 KWNH 182237
FFGMPD
AZZ000-NVZ000-CAZ000-190436-

Mesoscale Precipitation Discussion 1103
NWS Weather Prediction Center College Park MD
637 PM EDT Thu Sep 18 2025

Areas affected...southeastern California, southern Nevada, western
Arizona

Concerning...Heavy rainfall...Flash flooding likely

Valid 182236Z - 190436Z

Summary...Scattered instances of flash flooding are ongoing.=20
Locally significant impacts are possible. The ongoing threat
should continue through at least 05Z/10p PDT.

Discussion...Scattered to numerous thunderstorm activity continues
to drift generally northward across the discussion area. A
relatively focused cluster of storms has exhibited backbuilding
tendencies across southwestern Arizona, where a mature cold pool
has been established. The region remains under the influence of
deep southerly flow on the eastern edge of a disturbance centered
near the California coastline south of San Luis Obispo. The
southerly flow is maintaining a fetch of extremely moist and
unstable air from the Gulf of California, with pre-convective air (characterized by 1000-2000 J/kg MLCAPE and 1.5-2 inch PW)
continuing to support deep moist convection. Furthermore,
kinematics are modest enough to support slow storm motions and
continued backbuilding - especially near mature cold pool(s) and
near terrain-favored areas.

The ongoing scenario should continue to support locally heavy
rainfall in several areas. Local rain rates reaching 2 inches/hr
should continue. These rates should readily exceed FFG thresholds
across the region. Locally significant flash flood impacts remain
possible. Over time, widespread overturning and boundary layer
cooling should result in a lessening of convective coverage, but
this process should take several hours to play out. Deep
convection is likely to be ongoing through 05Z/10p PDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9LEkFD13iGcI__47ManaCAbp6z3eXQYxs2e_668ORkWFNJ49AOANlUT_TUNIppOw6S_W= Ny7YlvCbE6vWlrtXHe0L6rc$ for graphic product...

ATTN...WFO...FGZ...HNX...LOX...MTR...PSR...SGX...TWC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 37331872 36591507 35901209 33411127 31371148=20
32481495 32501662 33571704 34401845 34921967=20
36382068 37292044=20

=3D =3D =3D
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AWUS01 KWNH 190343
FFGMPD
NVZ000-CAZ000-190930-

Mesoscale Precipitation Discussion 1104
NWS Weather Prediction Center College Park MD
1142 PM EDT Thu Sep 18 2025

Areas affected...Southeastern California...Far Southwest Nevada...

Concerning...Heavy rainfall...Flash flooding likely

Valid 190345Z - 190930Z

SUMMARY...A few more hours of slow moving, efficient heavy
rainfall, rates of 1"+/hr and spots of additional 2-3" possible.
Flash flooding remains likely. A few incidents of mud/rock slides
and considerable flooding remain possible.=20

DISCUSSION...GOES-W WV suite shows impressive deep layer cyclone
continuing to advance through California into the Great Basin with
broad area of anticyclonically curved outflow across the northern
half of the overall, indicative of the favorable outflow
environment. The core of the upper-low remains just southeast of
Monterrey Bay with stronger southwest and west-southwesterly flow
starting to sharpen the negative tilt trof through the lower San
Joaquin Valley toward the Inland Empire. This 250mb jet is
strengthening to 70-80kts, though eastern side jet streak with
favorable right entrance ascent pattern is sliding away and
divergence is reducing with time.=20

A strong shortwave/MCV had developed in the negative tilt/high
divergence region through the Antelope Valley and along the
Tehachapi Range and this continues to provide solid DPVA and
ascent while keeping easterly and southerly flow from 850 to 700mb
directed through the northern Antelope Valley toward the Indian
Wells, Rose Valley and perhaps into the Panamint Valley and
through Death Valley later into the overnight period. The
remaining unstable and increased moisture flux still is leaking
through the Imperial Valley into Barstow and through the Antelope
Valley...with some 500-1000+ J/kg of MLCAPE and Total PWats of
1.5" available for the MCV to maintain solid convection near the
MCV until crossing the higher terrain into Inyo county and toward
SW Nevada. Confluence along the southeastern edge directly under
the larger scale negative tilt trough will allow for more
scattered cells along effective flanking lines that still could
repeat but with slowly diminishing effectiveness toward 09z when
instability should be exhausted and core of upper-level trof has
swung northward. Still cells, particularly near the MCV will
have capability of 1"+/hr, which will likely continue ongoing
flash flooding conditions, but will slowly reduce in
coverage/magnitude through Death Valley into SW Nevada by 09z.=20
Additional 2-3" totals through the northern Antelope Valley toward
China Lake remain possible; incidents of mud/rock slides are still
possible in/near the stronger cores for a few more hours as well.

Further southeast toward the Colorado River Valley. A cluster of
thunderstorms has been gusting out being along just southeast of
the base of negative tilt trof. Better access to deeper moisture
and slightly enhanced instability may allow for a few of these
cells to propagate along the developed outflow/cold pool lifting
northward. Some weak divergence may support some scattered totals
to 1" but more likely, forcing will continue to reduce and overall
coverage is likely to become more widely scattered to isolated
with time as well. Still, desert/hard ground conditions may still
allow for an isolated incident of possible flash flooding.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-iDHdhX873ffv6ZOgtxsyJBKgHzq0gySuLRk_5vdJwnAuA5n2tHLHpZCAo6cQ-N0eIE7= wqvtEuumfkY2EwSYHW1eLhY$ for graphic product...

ATTN...WFO...HNX...PSR...SGX...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 37841691 37621630 36861580 36111558 35391525=20
34541505 33631499 33271545 33631631 34451700=20
34941754 35431818 36101868 36791864 37521772=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 190724
FFGMPD
AZZ000-191200-

Mesoscale Precipitation Discussion 1105
NWS Weather Prediction Center College Park MD
323 AM EDT Fri Sep 19 2025

Areas affected...Central Arizona...

Concerning...Heavy rainfall...Flash flooding possible

Valid 190720Z - 191200Z

SUMMARY...Increasing convective development within some
WAA/upslope out of weakly capped conditionally unstable airmass in
the Sun Valley.

DISCUSSION...GOES-E WV suite depicts a convectively enhanced
shortwave feature along the SE Mohave/W Yavapai county line still
with fairly symmetric outflow and shortwave trough extending
southeastward within the left exit of the strengthening WSW
upper-level jet that is cutting across the Lower Colorado River
Valley and southern Arizona into SW NM. Lingering surface heating
in proximity to the Phoenix Metro heat island and still enhanced
deeper layer moisture through the valley with some steepening
lapse rates aloft, has maintained a small pocket of 1500-2000 J/kg
of MUCAPE. The combination of the left exit ascent and DPVA from
the NNE advancing shortwave and trough axis has allowed for veered
700mb flow to ascend isentropically to destabilize into steepening
terrain.

The 925-850mb 15-20kt of ESE to SE flow has maintained the ample
moisture in the lower levels and contributed to the deeper layer
moisture flux convergence to help support the expanding convective
development noted with a few rapidly cooling CBs on 10.3um EIR and
scattered updrafts in the KIWA RADAR domain. Nose of the deeper
layer moisture in the sfc to 700mb layers on CIRA combined with
the 20-30kts of flow support flux for moisture loading through the thunderstorms with limited sub-cloud evaporation expected.

As such, localized rates of 1.25-1.5"/hr are possible, though
steering flow is fairly strong even in the diffluent left exit of
the jet, limiting individual cell's residency. Yet, the upstream
environment and general upslope flow for the passing wave/upper
level divergence should maintain a modest probability for upstream
regeneration to allow for some localized repeating over the next
few hours. As such spots of 1-2" totals may induce localized
flash flooding concerns particularly near steeper terrain in the
lower slopes of the Mogollon Rim or near any burn scars that dot
the area of concern.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!--W3iV5M4FZouwYySjHKU6ZDNK82yAOMwPoClkgJR6gZafLjH21XCVYhU8ZuEVMGCbl2= jBmEhjNWUdH4hMTPGHWMXr8$ for graphic product...

ATTN...WFO...FGZ...PSR...TWC...

ATTN...RFC...STR...NWC...

LAT...LON 35001160 34981079 34421008 33530971 32880979=20
32641024 32631110 33001168 33591217 34371218=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 191325
FFGMPD
AZZ000-191800-

Mesoscale Precipitation Discussion 1106
NWS Weather Prediction Center College Park MD
923 AM EDT Fri Sep 19 2025

Areas affected...Central AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 191323Z - 191800Z

SUMMARY...Small bands of locally training showers and
thunderstorms may continue for at least a few more hours.
Additional concerns for some flash flooding will exist this
morning.

DISCUSSION...GOES-W IR satellite imagery is showing a couple of
small southwest to northeast oriented bands of heavy showers and
thunderstorms impacting portions of central AZ. The activity is
mainly focused in between Phoenix and Winslow, with some impacts
noted into the southwest-facing flank of the Mogollon Rim.

The convection is embedded within a modestly unstable airmass with
MUCAPE values generally around 500 J/kg, and is aligned with a
corridor of somewhat focused moisture convergence associated with
the low to mid-level southwest flow regime that remains in place.
There is also proximity of left-exit region upper-jet dynamics
associated with the subtropical jet crossing far southern CA and
southern AZ which is generating at least some deeper layer ascent
over the region.

The ongoing convection may tend to linger this morning for at
least a few more hours given the upper-jet support, and there will
be continuing concerns for some smaller scale backbuilding and
training of convective cells. Anomalous moisture remains in place
early this morning, with PWs running near 2 standard deviations
above normal, and this will still help support heavy rainfall
rates that may reach 1 inch/hour with the stronger storms.

Given the cell-training concerns, some additional short-term
amounts of up to 2 inches cannot be ruled out for this morning.
This may result in some additional localized concerns for flash
flooding with impacts primarily to the normally dry washes and
burn scar locations.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4Zfl9qYtjFV0qRQi9IKv8_XLv_Xkat1Con5l6j1oQ53KFSJ-eDn-KreeNEw-MzJdND1j= gdhXUgTuK_BlkTfe_AKIKqE$ for graphic product...

ATTN...WFO...FGZ...PSR...

ATTN...RFC...STR...NWC...

LAT...LON 35551100 35191020 34431013 33911083 33571236=20
34031303 34721302 35271219=20

=3D =3D =3D
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AWUS01 KWNH 191646
FFGMPD
TNZ000-MSZ000-ARZ000-TXZ000-192245-

Mesoscale Precipitation Discussion 1107
NWS Weather Prediction Center College Park MD
1245 PM EDT Fri Sep 19 2025

Areas affected...Southern AR...Northern MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 191645Z - 192245Z

SUMMARY...A localized and mainly urban concern for flash flooding
will exist through this afternoon from pockets of slow-moving
thunderstorms.

DISCUSSION...The latest satellite and radar imagery shows a couple
of different broken areas of slow-moving thunderstorm activity
that may tend to grow a bit upscale going through the late
afternoon hours. One cluster is near the Arklatex region with
convection becoming a bit better focused across southwest AR, and
there is a second area over parts of far eastern AR and into
northwest MS. All of this activity is generally focusing along
outflow boundary activity that was generated from earlier
convection this morning, but also with the aid of improving
boundary layer instability.

MLCAPE values along the wavy outflow boundary orientation across
the region have risen to as much as 1000 to 1500 J/kg, with some
of the better instability focused closer to the Arklatex in closer
proximity to a wave of low pressure that is seen in surface
observations.

While the low-level flow is quite weak, there is some modest MCV
energy ejecting east into southwest AR which coupled with the
low-level boundary and improving thermodynamic environment via
solar insolation may help allow for convection to expand in
coverage off to the east across southern AR with eventually some
connection potentially to the ongoing activity downstream over
northwest MS.

The latest hires model guidance has a very poor handle of the
current activity, but the cell-motions are rather slow with some
hints at some localized backbuilding cell character. Given the
moist and unstable environment, some rainfall rates will be
capable of reaching 2 inches/hour, and some localized storm totals
by later this afternoon may be capable of reaching 3 to 4 inches.

Generally, any flash flooding threat with these thunderstorms this
afternoon is expected to be localized and primarily an urban
concern.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6icwqmFIm70mG9zJH3xXG-KXhQWsnjF4AmrskKhcdfR4kOguDjh1Z6Bqd92Eb5Z_a-jm= Q3Y7oUwsUyQ7HMhk7taMsIw$ for graphic product...

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ALR...ORN...TUA...NWC...

LAT...LON 35008867 34818821 34218826 33788896 33498986=20
33299109 33219231 33309378 33619447 34079432=20
34429386 34659272 34749169 34779084 34888978=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 191802
FFGMPD
TXZ000-NMZ000-AZZ000-UTZ000-NVZ000-CAZ000-200000-

Mesoscale Precipitation Discussion 1108
NWS Weather Prediction Center College Park MD
200 PM EDT Fri Sep 19 2025

Areas affected...Far Eastern CA...Far Southeast NV...Northern and
Eastern AZ...Western and Central NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 191800Z - 200000Z

SUMMARY...A gradual increase in heavy shower and thunderstorm
activity is expected going through the afternoon hours which will
bring a concern for mainly isolated areas of flash flooding. This
will include potential impacts to dry washes and burn scar
locations.

DISCUSSION...The GOES-E WV suite shows mid-level shortwave energy
gradually ejecting off to the east across northern and eastern AZ
and into western NM which should interact with the diurnal heating
cycle today to yield scattered areas of heavy showers and
thunderstorms.

SBCAPE values are locally already upwards of 1000 to 2000 J/kg
across southeast AZ, with adjacent areas of western NM also
destabilizing rather rapidly due to strong diurnal heating. In
fact, the latest visible satellite images are showing an
increasingly agitated CU field beginning to take shape across
these areas, and convective initiation will likely be taking place
within the next hour or two near areas of higher terrain which is
also suggested by the latest AI-based LightningCast output.

PWs across the region remain anomalously high with values 1.5 to
2.5 standard deviations above normal across southern AZ into
western NM, and this coupled with the increasing boundary layer
instability will favor heavy showers and thunderstorms with rates
as high as 1 to 2 inches/hour.

The 12Z hires CAM consensus indicates that convection will
initially be more terrain-focused, but will also be advancing off
the terrain into the open desert locations where forward
propagation off to the east and southeast will be expected. Some
modest effective shear will be in place, and some loosely
organized multicell convection is expected given the
instability/shear environment.

Some localized storm total rainfall amounts where convective cells
become anchored near the terrain may reach as high as 2 to 3
inches, otherwise some spotty 1 to 2 inch amounts will be
expected. Isolated areas of flash flooding will be possible going
through this afternoon, and this may include impacts to dry washes
and burn scar locations.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5x7e-3EkWsj3wL4sfi9ksFTypKgHpL4DHNXOKUHR65PSmQzc_k40We2WIVEskwTFZqmX= cB6dBYWnE9Tp2F-qgJKFT-s$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...MAF...PSR...SLC...TWC...VEF...

ATTN...RFC...FWR...RSA...STR...NWC...

LAT...LON 37071337 36871226 35851080 35610934 35620716=20
35080572 34310476 33470443 32610444 31980492=20
31750662 31440763 31060900 31171080 31871192=20
32721243 33511316 34151458 35261542 36221527=20
36981437=20

=3D =3D =3D
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AWUS01 KWNH 200027
FFGMPD
TXZ000-NMZ000-AZZ000-UTZ000-NVZ000-CAZ000-200426-

Mesoscale Precipitation Discussion 1109
NWS Weather Prediction Center College Park MD
826 PM EDT Fri Sep 19 2025

Areas affected...central/southern New Mexico, southern through
northwestern Arizona, far southern Nevada

Concerning...Heavy rainfall...Flash flooding possible

Valid 200026Z - 200426Z

Summary...Isolated flash flood potential should continue for a few
more hours (through 04Z/10p MDT).

Discussion...Isolated, deep moist convection continues to drift
slowly eastward across the discussion area. Spots of 1 inch/hr
rain rates are noted with the most dominant and slowest-moving
activity (as estimated per MRMS). These rain rates have
occasionally fallen on locally sensitive areas (i.e., burn scars,
low-lying areas), posing a risk of excessive runoff and flash
flooding. Isolated flash flood potential continues in the near
term.

Models/observations suggest that most of the ongoing activity
should be diurnally driven, with a downward trend in both
intensity and coverage expected through the early overnight hours.
Most of the convective threat should diminish through 04Z. Flash
flood potential should also persist through that timeframe, while
becoming even more isolated thereafter.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_KOjLdmu83W7PgRi4gei56feCI1UhDrD3AiVbUx3ZrDlcV7TmuLs6ZvdQQeGZewXro3t= Aano8mpyFA5NxYRJahdQhdg$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...GJT...LUB...MAF...PSR...SLC...
TWC...VEF...

ATTN...RFC...FWR...RSA...STR...NWC...

LAT...LON 37731346 36941045 35841103 34451128 33890776=20
34720650 34660422 33790297 30800370 30600515=20
31450757 31030849 31471143 32441369 34761537=20
36691580 37671447=20

=3D =3D =3D
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AWUS01 KWNH 200237
FFGMPD
OKZ000-KSZ000-200800-

Mesoscale Precipitation Discussion 1110
NWS Weather Prediction Center College Park MD
1037 PM EDT Fri Sep 19 2025

Areas affected...South-central Kansas & Adj. North-central
Oklahoma...

Concerning...Heavy rainfall...Flash flooding possible

Valid 200240Z - 200800Z

SUMMARY...Warm advection thunderstorms with some short-term
training potential may result in a streak of 2-3" totals and
possible localized flash flooding concerns overnight.

DISCUSSION...02z Surface analysis shows a developing wave over
west-central KS with a stationary front angling southeast across
south-central KS into far northern Oklahoma. Surface to boundary
layer winds are starting to strengthen from the south, with
veering with depth. Enhanced moisture and slightly higher theta-E
axis exists across southwest KS and into the OK and far northern
TX panhandle and Northwest OK before reducing slightly. As such a
pool of enhanced unstable air with MUCAPEs up to 2000 J/kg exist
in warm sector. As surface flow veers near the front, flow is
increasing moisture flux convergence to overcome the reduced
capping in the vicinity of Lane/Gove and Ness counties. GOES-E
10.3um shows cooled overshooting tops cooling to -65C and
back-sheared anvil indicative of slow moving, rotating updrafts
with tops.

WV suite also denotes strong northwesterly flow aloft at the far
upwind edge of the exiting closed low over the Midwest but ahead
of the ejecting wave out of UT/CO, providing solid divergence
aloft while also maintaining favorable upwind energy to support
backbuilding of the convective complex. Deep layer steering is
faster than a traditional WAA/training complex and may limit
residency for extreme totals; the rotating updrafts' propagation
is reduced by 5-10kts from the mean flow (per Bunker's right mover
propagation vectors) and are aligned fairly close to the
orientation of the surface front and orthogonal to the
strengthening LLJ to support some repeating. Total moisture is
also a bit shallow at 1.25-1.4" and while flux convergence is
enhanced to the stronger updrafts, overall rainfall rates are
likely to be between 1.5-1.75"/hr. As such, streaks of 2-3" are
probable, especially if the back-building can be maintained and
ordination does not deviate much from NW to SE.
Combine that with FFG values of 1.5-2"/hr and 2-3"/3hrs (steadily
increasing from NW to SE into OK), spots of flash flooding are
considered possible through the overnight periods.=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4vCgITYds8oV0CwYQFt-T5kWn4AID1PiVICOkc-oVfI0ZP99yNHbJjU_OSvPJC1bHurM= 5gqXbqMqamjCyFMuybrGcJM$ for graphic product...

ATTN...WFO...DDC...GLD...ICT...OUN...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39000054 38829992 38559916 38289825 37919753=20
37239688 36699710 36519810 37049927 37770015=20
37930032 38440072 38770087=20

=3D =3D =3D
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AWUS01 KWNH 200355
FFGMPD
NVZ000-200730-

Mesoscale Precipitation Discussion 1111
NWS Weather Prediction Center College Park MD
1155 PM EDT Fri Sep 19 2025

Areas affected...West-central Nevada...

Concerning...Heavy rainfall...Flash flooding possible

Valid 200355Z - 200730Z

SUMMARY...Short-term training with rates up to 1"/hr and localized
totals to 1.5" may pose localized flash flooding concern for the
next few hours.

DISCUSSION...GOES-W WV suite shows further elongation and
degeneration of the larger scale western trough across northern
California into the Great Basin. At the col between the two
larger vorticity centers resides a weak confluence region from
700-500mb near the intersection of Nye, Mineral and Esmeralda
counties. Deep layer confluence at the tailing edge of the
upper-level trough, still has some sufficient DPVA as the shear
axis lifts across the ridge line of the California Sierra Nevada
Range. In the lowest levels, surface Tds remain in the low 50s
and depth of moisture still remains well above normal with Total
Pwat values of 1-1.1", with the bulk below 700mb as Tds at 700mb
remain around 5C. Additionally, RAP analysis suggests a weakly
capped pool of 500 J/kg of MLCAPE remains. The confluence though
850-700mb is supporting sufficient convergence to overcome the
weak low level capping and shallow thunderstorms continue to burst
along this axis with further shallower activity extending
northwestward toward Pershing and northern Churchill counties.=20
Rates up to 1"/hr are possible and given cooling tops to -50C
maybe ongoing.=20

Deep layer flow from the southwest will steer any activity
northeastward for some short-term training potential...with
maximum totals of 1-1.5" possible. Low level inflow remains weak
but sufficient through the valleys parallel to the CA/NV border to
maintain a few more hours of further shallow development and
training capability. Given FFG values are less than .75"/hr and
less than 1-1.5"/3hrs, flash flooding is considered possible along
this training axis, though persistent moderate showers may allow
for other atypical stream flows further into the 700-500mb
confluence zone toward the north-northwest in west-central NV.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-Cam6uYz8tjFg8DvDCyzYnU1nxbiJZMnp6wl7hf7Ggt8qZBA1dmro-kw-fXlzgqe4p2M= _OKlAb5k5P36GHDOPIjdPPs$ for graphic product...

ATTN...WFO...LKN...REV...VEF...

ATTN...RFC...RSA...NWC...

LAT...LON 40401887 40331754 39711678 39101675 38411713=20
37831799 38161842 39181838 39951897=20

=3D =3D =3D
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AWUS01 KWNH 210210
FFGMPD
MOZ000-ARZ000-OKZ000-KSZ000-210800-

Mesoscale Precipitation Discussion 1112
NWS Weather Prediction Center College Park MD
1009 PM EDT Sat Sep 20 2025

Areas affected...Northeast OK...Southwest MO...Northwest AR...Far
Southeast KS...

Concerning...Heavy rainfall...Flash flooding possible

Valid 210210Z - 210800Z

SUMMARY...Increasing WAA from strengthening low-level jet
intersecting pool of moist/unstable air. Favorable mid-level flow
may support training and isolated back-building/cell mergers to
support

DISCUSSION...GOES-E WV suite shows a subtle shortwave feature
moving along the central OK/KS boarder providing some mid-level
DPVA and positive ascent profiles downstream, coincident with
early evening low-level jet acceleration up to 20kt and eventually
veering more southwest to northeast and into the 30kt range. This
ascent is interacting with an old linger outflow boundary from
this morning's activity that connects from the surface front just
east of AVK toward SWO, MKO, FSM and more east across central AR.=20
Enhanced moisture of upper 60s to even mid 70s Tds with still some
remaining higher surface temperatures maintains a pool of
2000-2500 J/kg of MLCAPE across NE OK. The ascent pattern
convection has been pressing eastward into Osage county and
isolated pre-cursory cells north of Tulsa have been fairly
stationary in a 500-1000mb thickness ridge, that supports some
upstream redevelopment. Stronger updrafts and low level moisture
has made the cells fairly prolific/intense with hourly rates up to
2"/hr, with some localized observations over 3" near
Collingsville. This activity is likely to become a bit more
progressive with time, but localized totals may intersect areas
saturated this morning and have lower FFG values of 1.5"/hr and
less than 3"/3hrs, suggesting increased run-off is possible.

Further northeast, the northeast edge of the LLJ combined with the
northern edge of this morning's rain foot has concentrated
flow/convergence to support a NW to SE oriented 925-850mb FGEN
band. The convergence along which has sprouted some elevated
convection along the northeast edge of the higher instability air.
Deeper layer flow, here initially will support NW to SE cell
motions allowing for some potential training across SW MO/NW AR.=20
Spots of 2-3" may be possible, but eventual backing of the deeper
layer flow will reduce orthogonal ascent convergence and cells
from NE OK, will slide northeast and meld/merge. Rates may
trickle up to 1.75-2"/hr for these short-term mergers, but given
more rugged terrain with low water crossings, there is some
potential for possible incident or two of localized flash flooding
through the overnight period here as well.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_xp65VQ2MNcpbph3TQEkY66KmhWeulAAQwOxxAycrLMAfmHAZREsooxCtV72-ZYUMn6W= wuxj_HVMHjB-3iXlzKTKUro$ for graphic product...

ATTN...WFO...ICT...LZK...SGF...TSA...

ATTN...RFC...KRF...ORN...TUA...NWC...

LAT...LON 37469484 37159307 36649217 36029197 35679252=20
35869334 35979438 35819600 36279667 36859667=20
37239626=20

=3D =3D =3D
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AWUS01 KWNH 210708
FFGMPD
MOZ000-ARZ000-211130-

Mesoscale Precipitation Discussion 1113
NWS Weather Prediction Center College Park MD
308 AM EDT Sun Sep 21 2025

Areas affected...Northwest and north-central Arkansas...Far
Southern Missouri...

Concerning...Heavy rainfall...Flash flooding possible

Valid 210715Z - 211130Z

SUMMARY...Mature MCS continues to be fueled by upstream unstable, warm-advection for a few more hours. Additional 2-3" totals over
saturated grounds will continue to pose localized flash flooding.

DISCUSSION...Regional RADAR mosaic shows a mature MCS with forward
propagating outflow boundary convection along the southern flank
of the complex from Madison to Marion counties in N AR. Resultant
Meso-high is reducing residency for the squally line, however, VWP
continues to depict favorable 15-25kt inflow from the southwest
(out of NE OK), where the remaining pool of moderately unstable
air, higher low level theta-E air resides. RADAR denotes this
with the upwind edge lifting northeast across far NW AR,
potentially back across the most saturated zones of SW MO and NW
AR. This while remaining in fairly diffluent flow aloft at the
splitting of the upper-level jet and right entrance of a 50kt
speed max across far SE KS into western MO; these features will
help to maintain the upwind WAA for a few more hours, but
divergence and remaining unstable air should slowly reduce the
convective vigor of the overall complex in the next 2-3 hours.=20=20

Still, ample deep layer moisture and 1000-1250 J/kg of unstable
air with the strength of flux will maintain some rainfall
efficiency toward 1.5"/hr. As deeper layer steering flow backs
from westerly to southwesterly, current orientation of the outflow
boundary may yield some short-term training as well, mainly across
saturated areas from this round, but also earlier Saturday
morning. An additional 2-3" locally (particulalry along the
upwind edge of the complex) will continue to pose a localized
flash flooding risk through the late overnight period (3-4 hrs).=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-8EvAbxrjlXTy_-lIO4sDca2_KC1sDBToAAu5h3GJYPj3pBIV-MYRMusvaMuUyNTiovg= UacmOnKFKUi2p27rH1SeGvU$ for graphic product...

ATTN...WFO...LZK...SGF...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 36879333 36719223 36529136 36159109 35659117=20
35429171 35309264 35389383 35629431 36389445=20
36789396=20

=3D =3D =3D
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AWUS01 KWNH 210858
FFGMPD
KSZ000-211330-

Mesoscale Precipitation Discussion 1114
NWS Weather Prediction Center College Park MD
457 AM EDT Sun Sep 21 2025

Areas affected...Central Kansas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 210900Z - 211330Z

SUMMARY...A few scattered incidents of flash flooding are possible
as cells capable of 1.5"/hr may repeat/train over the next few
hours. A spot or two of 2-3" totals will near FFG, suggesting
isolated localized flash flooding is possible.

DISCUSSION...GOES-E WV suite depicts a very broad area of large
scale diffluence across much of Kansas, as a strong 90kt 250mb jet
turns southeast out of CO into NW TX; while a digging northern
stream trough and shortwave crossing west-central NEB provide
large scale divergence ascent across KS. Toward the surface, a
poorly defined surface boundary extends from the Kansas City Metro
southwest toward a low near Wichita, then extends due west before
turning north across eastern CO. Broad southerly flow across the
southern Plains remains about 20-25kts providing moderate moisture
flux, with the nose of the moisture axis centered along 98W. CIRA
LPW shows the enhanced pockets of moisture from surface (Tds in
the low to mid 60s throughout KS/OK), overlap with maxima across
the 850-700mb layer along the KS/OK border and 700-500mb in
central OK...resulting in a 1.5" total PWat corridor toward the
area of concern fluxed on the LLJ.

Steeper mid-level lapse rates has provided broad area of
conditionally unstable air with 1000-1250 J/kg of MUCAPE across
the area of concern. However, maximized convergence has resulted
in two west to east moisture convergence axes; the first lower,
just near the boundary layer has activated scattered, narrow
updrafts with a few stronger isolated near surface rooted embedded
cells across SW KS that have greater cloud depth an moisture
availability. This, while speed convergence and weak FGEN ascent
could tap elevated unstable air near 800mb in proximity to I-70
corridor. As such, regional RADAR shows greater convective vigor
over a broader area, further north. Rates up to 1.25-1.5"/hr are
probable with the elevated cells. Both areas have favorable
orientation to the deeper west to easterly flow and with solid
outflow aloft, should maintain on the modest remaining instability
for the next few hours. Given repeating/training potential,
widely scattered totals of 3"+ are possible.

Hydrologically, FFG values are 1.5"/hr and about 2.5"/3hrs.
However, there are areas of recent heavier rainfall that have
likely rebounded a bit too quickly as noted in NASA SPoRT 0-40cm
soil ratios in the 50-60% range from Hodgeman to Stafford counties
and further south across Pratt, Barber, Kingman and Harper
counties from last night's complex. Given the rates and cell
orientation, FFG exceedance and localized flash flooding is
considered possible, until southerly moisture flux convergence
becomes too weak to maintain convective vigor

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_ZkBD8gzxo8ijy8VPzOzBVt_tpjly5t5uMLSvjb012_CRZ9Ni9J3wsQDVJbrSZBf7nHI= m0F4kJOLSHAMUStTLGYuhh8$ for graphic product...

ATTN...WFO...DDC...GID...ICT...TOP...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39289872 39279787 39249743 39039690 38709640=20
38359624 37979643 37699706 37569743 37409810=20
37279902 37379974 37770046 38240049 38640018=20
39069969=20

=3D =3D =3D
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AWUS01 KWNH 220732
FFGMPD
ARZ000-OKZ000-221300-

Mesoscale Precipitation Discussion 1115
NWS Weather Prediction Center College Park MD
331 AM EDT Mon Sep 22 2025

Areas affected...Eastern Oklahoma...Western to Central Arkansas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 220730Z - 221300Z

SUMMARY...Area of concern will remain in favorable region for
upstream redevelopment and repeat track clusters of storms. Rates
to 1.5"/hr and spots of 2-3.5" suggest an incident or two of
localized flash flooding is possible through daybreak.

DISCUSSION...GOES-E WV suite denotes compact shortwave at base of
broader scale long wave trough is exiting south-central MO, with
trailing confluence trough through the low to mid-levels lingering
across west-central AR into far eastern OK. A few stronger
clusters with rates of up to 1.5"/hr and similar localized totals
have been noted along this axis for much of the overnight period,
helping to saturate the upper soil profiles and locally reduce
FFG. However, recent 3.9um/10.3um IR loops show increasing
mid-level cloudiness and agitated shallow convective environment
across the upstream edge of the ongoing clusters. RAP analysis
denotes a weakening cap with CINH reducing below 15 J/kg across
western AR into far Northeast TX, generally coincident with
instability and low to mid-level confluence axis. While, lapse
rates are limited, low level theta-E remains and supports
1000-1250 J/kg of MLCAPE trough this area and points west. CIRA
LPW and RAP analysis also note the deeper layer moisture axis
further west within the broader southwesterly 25-30kt LLJ across
central to eastern OK, though overall deep layer confluence also
depicts a pool of moisture to 1.7" along the best convergence over
western AR.

Aloft, the speed max of the subtropical jet is reaching the apex
of the ridge further upstream over CO, but the exit of the jet is
digging southward across central OK/NE TX, resulting is broadening
left exit divergence to support upstream redevelopment and slow
veering of the LLJ further increasing low-level convergence. As
such, expectation for further upstream development is expected for
the next 3-6hrs. Deep layer steering mean flow is toward the
northeast as the shortwave exits, however, the strength of the
approaching jet has sharpened the 500-1000 thickness ridge to the
west and propagation vectors are starting to turn upstream to the
low-level inflow, bending the storm track vectors more west to
east. This should allow for upstream thunderstorm clusters that
do develop to once again track through areas recently saturated.=20
Rates of 1.5"/hr and potential for additional 2-3" totals suggest
scattered incidents of localized flash flooding are becoming
increasingly possible through the remainder of the overnight
period. There remains some uncertainty to the latitude of the
redevelopment, but any activity further north will also intersect
areas saturated over the last two nights as well into NW,
north-central AR.=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8BblS9xxEqPsw_KBtK_DrEPLT3ltN387XEmCj8W7t-snZuSyK92wcWmOEthTaSIkNEDq= WcUO_g9tzGv6ePFuxOJ77HY$ for graphic product...

ATTN...WFO...LZK...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 36169515 36049332 35769228 35319175 34679197=20
34509246 34509322 34699424 35039523 35669561=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 221301
FFGMPD
ARZ000-TXZ000-OKZ000-221740-

Mesoscale Precipitation Discussion 1116
NWS Weather Prediction Center College Park MD
900 AM EDT Mon Sep 22 2025

Areas affected...eastern OK into central/northern AR

Concerning...Heavy rainfall...Flash flooding likely

Valid 221259Z - 221740Z

SUMMARY...Continued training of showers and thunderstorms will
maintain an increased potential for flash flooding from portions
of eastern OK into central/northern AR over the next 3-5 hours.
Hourly rainfall will range from 1 to 3 inches.

DISCUSSION...Radar imagery from 1230Z showed an ongoing cluster of thunderstorms over north-central AR, in the vicinity of I-40 to
the west of Little Rock. This area has been associated with
MRMS-derived hourly rainfall of 1 to 3 inches since at least 10Z
within areas of training. A second small cluster was located just
north of Dallas/Fort Worth while additional shower/thunderstorm
activity was developing over eastern OK. All of these areas were
located just north of an effective quasi-stationary front draped
from AR WSW into northern TX enforced by rain-cooled outflow. VAD
wind plots across the region highlighted 850 mb wind speeds of
20-30 kt from the SW across TX into AR but with veering toward the
WSW over TX since 10Z. Meanwhile, SPC mesoanalysis data from 12Z
indicated MLCAPE of 1000-1500 J/kg along and north and just north
of the effective front with short term RAP forecasts showing
weakening inhibition over eastern OK over the next few hours with
the onset of daytime heating and continued low level moisture
advection into the region.

Short term RAP forecasts are in line with weakening of the low
level jet through 18Z but the boundary will remain and some degree
of overrunning should continue over the next few hours with a
strongly favorable diffluent/divergent region aloft over AR ahead
of a sub-tropical jet max over KS/OK. Some expansion of
shower/thunderstorm activity is expected over eastern OK over the
next 1-2 hours with potential for training within the mean
westerly steering flow. Given the high precipitable water
environment (1.5 to 2.0 inches) and sufficient instability,
pockets of training are likely to continue at least localized
areas of flash flooding over the next 1-2 hours with possible
continuation of the flash flood threat through 17Z, though
confidence beyond the next 1-2 hours is lower than average given
poor model handling of the ongoing activity.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7mMb_MBCtX5vSFb7ebwCcUwmlv3mlFQoNNIOP_o31Z9Ie_pL5TBxwBb1D-0tU0iRsX73= N0maKVVqiLfDKtL_EyRyz58$ for graphic product...

ATTN...WFO...FWD...LZK...MEG...OUN...SHV...TSA...

ATTN...RFC...FWR...ORN...TUA...NWC...

LAT...LON 36049368 35959248 35739092 35419054 34569097=20
34409275 34289423 33669526 32999622 33179711=20
33599726 34759684 35579603 35999493=20

=3D =3D =3D
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AWUS01 KWNH 222305
FFGMPD
NMZ000-230200-

Mesoscale Precipitation Discussion 1117
NWS Weather Prediction Center College Park MD
704 PM EDT Mon Sep 22 2025

Areas affected...Portions of Central and Eastern NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 222304Z - 230200Z

SUMMARY...Bands of heavy showers and thunderstorms will be
impacting central and eastern NM over the next couple of hours.
Some flash flooding impacts may occur over especially portions of
the Sacramento Mountains where there are sensitive burn scar
locations.

DISCUSSION...The latest GOES-E IR satellite imagery along with
radar shows a couple of bands of heavy showers and thunderstorms
moving rather progressively off to the east across central NM.
This activity is advancing east in conjunction with shortwave
energy traversing the southern Rockies and interacting with a
relatively convergent, moist and unstable boundary layer pooled
across central and eastern NM.

SBCAPE values are locally near 1000 J/kg with PWs across the
region running upwards of 1 to 2 standard deviations above normal.
Some shear is noted overhead with the belt of stronger shortwave
energy nearby, and this is favoring some loose organization of the
convection with bands of multicell activity.

Despite the progressive nature of the convection, this activity
will be capable of bringing heavy rainfall rates which will soon
impact the Sacramento Mountains and portions of the Lincoln
National Forest where there are multiple sensitive burn scar
locations. This includes the Blue 2, South Fork, Salt and McBride
burn scar complex, and notably near and adjacent to Ruidoso.

Rainfall amounts of as much as a 0.50 inch in 15 minutes will be
possible, with some spotty storm totals of up to 1 inch where any
repeating cell-activity occurs through early this evening. These
rains may result in there being some burn scar flash flooding
impacts as a result over the next 1 to 2 hours until the activity
passes off to the east.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6QEWH4X4cJCACaXajCgebzBFdObj0PLsGvdgycDMbAYD4-eeJ0khZyQnuz-wzT0vx6x3= xUrZGPGwDNp3gi-dv2fzSmU$ for graphic product...

ATTN...WFO...ABQ...EPZ...

ATTN...RFC...FWR...NWC...

LAT...LON 34480446 33940410 33560422 33140479 32850604=20
32880675 33110718 33440732 33800714 34270620=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 222314
FFGMPD
KSZ000-COZ000-230500-

Mesoscale Precipitation Discussion 1118
NWS Weather Prediction Center College Park MD
713 PM EDT Mon Sep 22 2025

Areas affected...Portions of Far Eastern CO and Western KS

Concerning...Heavy rainfall...Flash flooding possible

Valid 222313Z - 230500Z

SUMMARY...Developing and expanding clusters of heavy showers and
thunderstorms are expected going into the evening hours across
portions of far eastern CO and western KS. Isolated areas of flash
flooding will be possible.

DISCUSSION...Late-day GOES-E visible satellite imagery along with
regional radar data shows developing and gradually expanding
clusters of heavy showers and thunderstorms across parts of far
eastern CO and northwest KS, with the activity focusing along a
developing frontal boundary. Increasing low-level moisture
convergence is noted along this front, and the convection is
developing within a moderate to strongly unstable airmass
characterized by MLCAPE values of 1500 to 2500 J/kg.

This instability along with 30 to 40+ kts of effective bulk shear
is already favoring some supercell thunderstorm development, and
over the next several hours as upstream shortwave energy/forcing
arrives from central Rockies and crosses the High Plains, there
will be a favorable environment for expanding and organizing
clusters of multicell and supercell thunderstorms.

By early to mid-evening, the main convective threat area should
involve far eastern CO and western KS, but a combination of
cell-merger activity and upscale MCS development is expected in
time as DPVA/height falls provide stronger forcing in conjunction
with a strengthening southerly low-level jet across the central
Plains ahead of the aforementioned front. This will gradually
allow for the convective mass to expand off to the east and
southeast going through the overnight hours.

While much of the convection this evening will primarily be of a
severe nature, there will be sufficient levels of moisture
transport and convective cell organization to promote high
rainfall rates that may reach 1 to 2 inches/hour. Cell-merger
activity and localized cell-training concerns may foster there
being some rainfall totals of 3 to 4+ inches by mid-evening. This
is consistent with the 18Z HREF/12Z REFS suites of guidance.

As a result, there may be an isolated threat for some flash
flooding over the next several hours as these stronger multicell
and supercell thunderstorm clusters evolve.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9IJ6lg5u3UtcfLHVvR4vbV7rFLaQCb6tyJnIuXhtyRieIFnzk0e7ShbKimi-k8gEWlIH= KCoQQcTf82-USiTV5IvTXQc$ for graphic product...

ATTN...WFO...BOU...DDC...GID...GLD...PUB...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39710138 39670031 39479958 38769927 38109956=20
37950065 38300152 38400196 38680289 38800343=20
39250362 39500322 39620231=20

=3D =3D =3D
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AWUS01 KWNH 230106
FFGMPD
NEZ000-SDZ000-230630-

Mesoscale Precipitation Discussion 1119
NWS Weather Prediction Center College Park MD
905 PM EDT Mon Sep 22 2025

Areas affected...Southwest SD...Northwest NE

Concerning...Heavy rainfall...Flash flooding possible

Valid 230105Z - 230630Z

SUMMARY...Slow-moving heavy showers and thunderstorms may result
in a threat for isolated areas of flash flooding over the next
several hours.

DISCUSSION...The latest GOES-E IR satellite imagery shows cooling
convective tops across southwest SD in response to a combination
of amplifying mid-level shortwave energy and a nose of moderate
instability focused near a front. MLCAPE values of 1000 to 2000
J/kg are noted across the region along with an axis of moderately
strong moisture convergence.

Model guidance suggests a further amplification of mid-level
energy/height falls with a rather tight 700 mb circulation
forecast to evolve overnight along the SD/NE border with a slow
southward drift in time. This will help support a relatively
strong mid-level deformation zone around the western flank of the
low center, with a favorable axis of moisture convergence and some frontogenetical forcing working in tandem with the available
instability to support additional concentrated focus for heavy
showers and thunderstorms.

Rainfall rates with the convection over the next few hours will be
capable of reaching 1 to 2 inches/hour, and with the slow
cell-motions, some localized storm totals may reach 3 to 4 inches
which is consistent with the latest hires model guidance. An
isolated threat for flash flooding will exist where the heavier
rainfall totals materialize over the next several hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!591XiKxBXRChhYw7AD4xj8WZr883DGw6HhZ1CVNV_VSG5T2v_5HTGwA_s-p0GB7br9AN= P0w_s-4BeL3b1zTMoEAHZlE$ for graphic product...

ATTN...WFO...CYS...LBF...UNR...

ATTN...RFC...KRF...NWC...

LAT...LON 44570340 44480281 43950219 43330120 42820105=20
42670149 42620181 42480227 42100279 42310354=20
43080399 43570395 44140386=20

=3D =3D =3D
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AWUS01 KWNH 230231
FFGMPD
IAZ000-NEZ000-230800-

Mesoscale Precipitation Discussion 1120
NWS Weather Prediction Center College Park MD
1031 PM EDT Mon Sep 22 2025

Areas affected...Southwest Iowa...Eastern Nebraska...

Concerning...Heavy rainfall...Flash flooding possible

Valid 230230Z - 230800Z

SUMMARY...Slow moving/stationary cells to intersect back-building
upwind edge of southward moving squall line in IA. Strong
moisture flux convergence will support rates up to 2" and
localized spots of 2-4" resulting in scattered localized flash
flooding.

DISCUSSION...02z surface analysis shows a sharpening frontal zone
across northern IA, in particular in NW IA before front stalls
northeast of developing surface wave near Ord, NEB. This northerly
flow is opposed by strengthening south and southwesterly flow
across SE NEB and within 850mb 25-30kt LLJ. RAP analysis fields
show much of eastern NEB and SW IA remain fairly unstable, though
capped with over 2000 J/kg of MLCAPE. As FGEN/moisture flux
convergence continues to strengthen, the cap has already weakened
in a few places in E NEB for stronger cells to develop, but will
continue to expand with time. Combine this with outflow from
ongoing convective squall line in central IA, likely to further
build/expand convective coverage westward into the strengthening
WAA.

Aloft, the dominant closed low over the Great Lakes is breaking
eastward while the replacing stronger cyclone is building through
the Central Rockies. This has lead to a decoupling/de-phasing of
the longer wave trough and resulted in a mid-level col in the
flow. Stretching and overall DPVA remains to provide strong
ascent, though the deformation zone from 700-500mb will allow for
very slow cell motions with upstream back-building likely along
the flanking outflow boundaries from the cells themselves. The
strength of moisture flux convergence of 25-30kts and Tds in the
50s to mid 60s through 700mb supports total Pwats toward 1.75" and
convergence to allow for cells to be highly efficient with rates
of 2"/hr probable. The limited motions should also support
localized totals of 2-4" over 2-3hrs especially before the cold
front starts surging (mainly from east to west-southwest) through
the early overnight period.=20

While the area has been stricken by drought conditions, as NASA
SPoRT 0-40cm RSM values are at or below 10%, the steer magnitude
of rates on hard grounds will have limited infiltration initially
and support higher run-off potential. Combine this with hourly
FFG values around 1.5-2"/hr & 2-3"/3hrs, these scattered slow
moving cells initially will pose a possible localized flash
flooding concern though the early overnight period. As the front
presses cells south, shorter residency should limit totals but
isolated flash flooding will still be a problem in the area of
concern.=20


Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!81GcsSC-8A_pdUA78uSry6rllqC7eTr38gojJa-rTH5W9swqUOe8N6PS7T9sx2_ZiPLJ= aLjUo53Bar31VoghLkM4jQU$ for graphic product...

ATTN...WFO...DMX...GID...OAX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON 42179617 42129450 41919369 41309318 40639362=20
40649603 40259793 40699884 41469880 42039733=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 230441
FFGMPD
KSZ000-231015-

Mesoscale Precipitation Discussion 1121
NWS Weather Prediction Center College Park MD
1241 AM EDT Tue Sep 23 2025

Areas affected...Much of Western & Southern Kansas...Northern
Oklahoma...

Concerning...Heavy rainfall...Flash flooding possible

Valid 230445Z - 231015Z

SUMMARY...A highly dynamic environment will support strong
moisture flux into a deformation zone resulting in slow moving but
efficient rainfall production (rates to 1.75"/hr) resulting in
localized spots of 2-3"+ and possible scattered localized flash
flooding.

DISCUSSION...GOES-E WV shows core of developing larger scale
closed low over the Central Rockies with strong undercutting polar
jet energy across Colorado into the Central Plains.
Simultaneously, the apex of the subtropical jet has reached KS and
with broad anticyclonically curved baroclinic shield of cirrus
over much of northern KS and southern NEB, with occasional
overshooting tops breaking out through the canopy. An older
smaller scale shortwave exists in the increasingly divergent
portion of northern KS and will meld with southern stream
shortwave surging out of the TX/OK panhandles.

With all the moving parts in the mid-levels, the surface pattern
is lagging a bit being a bit further north for the frontal zone,
with a cold front surging down eastern CO, a surface wave in NW KS
is slow to advance southeast and with further surge of WAA across
south-central into E NEB; this results in a broad conditionally
unstable warm sector across much of western and central KS. With
the southwesterly surge of low to mid-level flow, the warm
conveyor belt/LLJ is strengthening and becoming increasingly
convergent across the KS/OK border though is starting to back from
southerly to southeasterly as the southwesterly drier air lifts.=20
This is sharpening a shear/stretching deformation zone across
west-central KS through toward north-central KS from TQK to HYS to
CNK. This will support strong deep layer moisture flux
convergence and with ample 1500-2000 J/kg of CAPE will allow for
stronger vertical development and potential for rates of
1.5-1.75"/hr, given flux of 1.5" PWs mainly loaded below 700mb.=20

As the 700-500mb low sets up along the lower-level deformation
zone, cell motions will be slow and eastward with potential for
some mergers/collisions so occasional embedded uptick toward 2"/hr
rates. The higher residency of a few hours to exhaust the
unstable air, should allow for localized totals of 2-3"+ perhaps
an isolated 4" total. There is a fairly sharp gradient of soil
saturation conditions across central KS being wetter further
south. Still, FFG values of 1.5"/hr and less than 3"/3hrs seem
approachable suggesting a few scattered incidents of flash
flooding are considered possible through the remainder of the
overnight period.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9XoGsiMKe81FpYQMuvFd2upn0BNKW47QqxUDv1AuhqGwSm4qZF2umCqEw5VkaoSVrytK= b6pFOrSRyeAC_hpDXcJ7GvU$ for graphic product...

ATTN...WFO...DDC...GID...GLD...ICT...TOP...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39499740 39369669 38579653 37849834 37820024=20
38210134 38620178 39130159 39350117 39340033=20
39239918 39299818=20

=3D =3D =3D
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AWUS01 KWNH 230451
FFGMPD
KSZ000-231015-

Mesoscale Precipitation Discussion 1121...Corrected
NWS Weather Prediction Center College Park MD
1250 AM EDT Tue Sep 23 2025

Corrected for Correction for Areas Affected

Areas affected...Western to Central Kansas....

Concerning...Heavy rainfall...Flash flooding possible

Valid 230445Z - 231015Z

SUMMARY...A highly dynamic environment will support strong
moisture flux into a deformation zone resulting in slow moving but
efficient rainfall production (rates to 1.75"/hr) resulting in
localized spots of 2-3"+ and possible scattered localized flash
flooding.

DISCUSSION...GOES-E WV shows core of developing larger scale
closed low over the Central Rockies with strong undercutting polar
jet energy across Colorado into the Central Plains.
Simultaneously, the apex of the subtropical jet has reached KS and
with broad anticyclonically curved baroclinic shield of cirrus
over much of northern KS and southern NEB, with occasional
overshooting tops breaking out through the canopy. An older
smaller scale shortwave exists in the increasingly divergent
portion of northern KS and will meld with southern stream
shortwave surging out of the TX/OK panhandles.

With all the moving parts in the mid-levels, the surface pattern
is lagging a bit being a bit further north for the frontal zone,
with a cold front surging down eastern CO, a surface wave in NW KS
is slow to advance southeast and with further surge of WAA across
south-central into E NEB; this results in a broad conditionally
unstable warm sector across much of western and central KS. With
the southwesterly surge of low to mid-level flow, the warm
conveyor belt/LLJ is strengthening and becoming increasingly
convergent across the KS/OK border though is starting to back from
southerly to southeasterly as the southwesterly drier air lifts.=20
This is sharpening a shear/stretching deformation zone across
west-central KS through toward north-central KS from TQK to HYS to
CNK. This will support strong deep layer moisture flux
convergence and with ample 1500-2000 J/kg of CAPE will allow for
stronger vertical development and potential for rates of
1.5-1.75"/hr, given flux of 1.5" PWs mainly loaded below 700mb.=20

As the 700-500mb low sets up along the lower-level deformation
zone, cell motions will be slow and eastward with potential for
some mergers/collisions so occasional embedded uptick toward 2"/hr
rates. The higher residency of a few hours to exhaust the
unstable air, should allow for localized totals of 2-3"+ perhaps
an isolated 4" total. There is a fairly sharp gradient of soil
saturation conditions across central KS being wetter further
south. Still, FFG values of 1.5"/hr and less than 3"/3hrs seem
approachable suggesting a few scattered incidents of flash
flooding are considered possible through the remainder of the
overnight period.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8CmRk1etGdEO6-eWZwsb5ll8cjyE_b2n0s0slx-Z4dZQhZWEBj494Vlkqh0ni14PBPwx= SYrLk1g74k_Uxy9CsqWAOWg$ for graphic product...

ATTN...WFO...DDC...GID...GLD...ICT...TOP...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39499740 39369669 38579653 37849834 37820024=20
38210134 38620178 39130159 39350117 39340033=20
39239918 39299818=20

=3D =3D =3D
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AWUS01 KWNH 230519
FFGMPD
OKZ000-KSZ000-231030-

Mesoscale Precipitation Discussion 1122
NWS Weather Prediction Center College Park MD
118 AM EDT Tue Sep 23 2025

Areas affected...Southern Kansas...Northern Oklahoma...

Concerning...Heavy rainfall...Flash flooding possible

Valid 230515Z - 231030Z

SUMMARY...Efficient, intense, quick-hitting thunderstorms capable
of sub-hourly totals of 1-2" and totals to 3"+ pose localized
flash flooding concerns through overnight period.

DISCUSSION...GOES-E 10.3um IR loop shows fast moving clusters of
thunderstorms with isolated overshooting tops cooling to -80C
across SW KS into NW OK. RADAR mosaic denotes the broadening arch
of these cells in advance of a fast moving southern stream
shortwave features exiting the OK Panhandle. The arch is an
alignment of mid-level DPVA ascent and strong confluent boundary
layer convergence of southwesterly flow off the high terrain and
broadening, but strengthening LLJ responding to the much larger
scale height-falls and organization of the closed low across the
Central Rockies. VWP and RAP analysis shows the strong deep
layer WAA veering with strengthening 30 to 35kt flow through
925-850mb convergent on this arch. Low 70s Tds at the surface,
60s through 850mb and even low 40s at 700mb shows convergence
though depth very well within animation of the CIRA LPW resulting
in 1.75" total PWats, but very strong deep layer flux convergence.
MLCAPEs over 3000 J/kg combined with strength of flux is
resulting in high rainfall generation/efficiency for these
expanding clusters.=20

Limiting factors are the strength of the flow, is resulting in
very quick cell motions of 30-40kts, limiting residency. However,
regional RADAR mosaic denotes the updrafts are broadening along
the length of the mean flow, increasing duration ever so slightly.
Currently, KDDC/KVNX suggest hourly estimates of 1-1.5", though
are steadily increasing given overall increase of deep layer
moisture. 03z HRRR suggests peak of 1.5-2" in 15 minutes across
south-central KS between 06-08z, which does not seem implausible
and aligns with 00z HREF 2"/hr probability of 40%. As such,
localized totals of 2-3" in 1-2 hours may result in localized
flash flooding conditions, especially given most areas within the
area of concern have 1hr FFG values at or below 2", with some
areas of south-central KS into northeast OK, slightly reduced
further to below 1.5", given recent rainfall. Still, the overall
speed of cells may result in a highly variant rainfall pattern
resulting in scattered incidents of flash flooding overnight.=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_yMbKuqR-e7d7sKqPNw_G-AL1eLFqdnLf-d_vov8B6wRoUxvkp5L8n8GikXRHdVpSuvJ= Wn5O2RWDIQbt_MG4Xb8sd5E$ for graphic product...

ATTN...WFO...DDC...ICT...OUN...TSA...

ATTN...RFC...TUA...NWC...

LAT...LON 38229763 37959602 37539537 36979526 36529543=20
36229603 36149709 36199823 36349917 36979966=20
37519987 38019910=20

=3D =3D =3D
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AWUS01 KWNH 231000
FFGMPD
MOZ000-KSZ000-NEZ000-231500-

Mesoscale Precipitation Discussion 1123
NWS Weather Prediction Center College Park MD
600 AM EDT Tue Sep 23 2025

Areas affected...Northeast Kansas...Northwest Missouri...Far
Southeast Nebraska...

Concerning...Heavy rainfall...Flash flooding possible

Valid 231000Z - 231500Z

SUMMARY...Broad scale over-turning of remaining unstable air will
have short-term rates of up to 2"/hr and localized totals to 2-3"
in 1-3 hours, resulting in possible localized flash flooding.

DISCUSSION...GOES-E WV suite depicts broad diffluent region
downstream of strengthening deep layer cyclone over the central
Rockies. An embedded shortwave is sharpening and vertically
stretching within the divergent pattern aloft, providing solid
DPVA across northeast KS into far southeast NEB and northwest MO.
This area has remained conditionally unstable and capped through
the early overnight period with broad 2000 J/kg MUCAPE reservoir
along and southwest of the Missouri River Valley.

Outflow boundary and southward sinking cold front out of IA and
east-central NEB initially provided sufficient convergence along
the northeast edge of the instability core and rapid expansion has
occurred over the last hour or so as southwesterly WAA has further
impinged on the area. Strong ascent and ample deep layer moisture
has supported localized rates of 1.5-2"/hr and with very
slow/stationary cell motions, generally only moving due to
outflow/propagation, an hour or so of intense rainfall may again
result in widely scattered 2-3" totals in 1-3 hours.=20

Additionally, as the southern stream shortwave melds with the
northern stream feature, effectively elongating the mid-level
trough toward a longer negative tilt orientation, but also
strengthened southwesterly flow and deep layer convergence with
the core of the southerly LLJ and effective moisture flux.=20
Leading edge convergence is also building a west to east oriented
arc of thunderstorms along the southwestern edge of the unstable
air, slow northward migration and intersection with the convective
outflow from the northwest will see a larger slab ascent with
broad overturning of the remaining 1.5-1.75" total Pwats in the
column and likely result in similar hourly rates up to 2"/hr but
likely to diminish quickly thereafter, likely resulting in widely
scattered pockets of 2-3" totals further southwest across
northeast KS toward the KC Metro. The sheer rates may result in
localized flash flooding conditions, especially near urban
centers.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4pdf2qDoqkSdexjFO5QAtESE9qpn9JhQgDznwHGojPUQ9CdjCkId2y0f3Gli7Z4kI3Fj= CNK4mAUJtxG9CDmo2NPoxhI$ for graphic product...

ATTN...WFO...EAX...GID...OAX...TOP...

ATTN...RFC...KRF...NWC...

LAT...LON 40709689 40639608 40299516 39759444 39249384=20
38599419 38469488 38769571 39159679 39429830=20
40279804 40599744=20

=3D =3D =3D
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AWUS01 KWNH 231210
FFGMPD
MOZ000-ARZ000-OKZ000-KSZ000-231709-

Mesoscale Precipitation Discussion 1124
NWS Weather Prediction Center College Park MD
810 AM EDT Tue Sep 23 2025

Areas affected...southwestern Missouri, far northern Arkansas, far
northeastern Oklahoma

Concerning...Heavy rainfall...Flash flooding possible

Valid 231209Z - 231709Z

Summary...Isolated, spotty flash flood potential exists for a few
hours this morning (through 17Z/noon CDT).

Discussion...A loosely organized complex of storms was located
near the MOKSAROK (Missouri/Kansas/Oklahoma/Arkansas state border
region) this morning. The loosely organized nature of this
complex was favoring limited amounts of convective training -
particularly in southwestern Missouri where downstream
thunderstorm cells were developing along a warm front near the
region very close to the Springfield area. Spots of 1 inch/hr
rain rates were being detected/estimated per MRMS within the
region of training. Coincidentally, these rain rates were falling
across areas of the Missouri Ozarks that can be flood prone in
sensitive areas. With FFG thresholds in the 1.5 inch/hr range in
spots, any modest uptick in rain rates could cause isolated flash
flood issues in the short term.

The longevity of this flash flood risk is a bit in question,
however. As storms continue to move/propagate east, they will
eventually depart the region of greatest combined instability and
low-level convergence (currently focused along the OK/KS border).
Furthermore, radar data doesn't suggest that ongoing activity has
sufficient organization for persistence deeper into the
Missouri/Arkansas Ozarks east of the U.S. Highway 65 and 63
corridors - especially in the absence of any larger-scale ascent.=20
Thus - an already isolated flash flood risk may gradually become
more conditional with time and eastward extent across the
discussion area.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4YHEa8QUip9B0zHTI9fAaeoGmUgMGi9cFygNsngIv5YUOVxu6DX4SS7VFSQjub_tLoK-= CUm_kqXQ0K6SBPpkh6J0QUU$ for graphic product...

ATTN...WFO...EAX...ICT...LSX...LZK...MEG...PAH...SGF...TSA...

ATTN...RFC...KRF...MSR...ORN...TUA...NWC...

LAT...LON 38359359 38089199 37389075 36539030 35999152=20
35829445 36369597 37399511 38219470=20

=3D =3D =3D
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AWUS01 KWNH 231743
FFGMPD
MOZ000-ARZ000-OKZ000-KSZ000-232342-

Mesoscale Precipitation Discussion 1125
NWS Weather Prediction Center College Park MD
143 PM EDT Tue Sep 23 2025

Areas affected...southwestern Missouri, western Arkansas, eastern
Oklahoma

Concerning...Heavy rainfall...Flash flooding likely

Valid 231742Z - 232342Z

Summary...Convective redevelopment is expected over the course of
the afternoon, with local areas of potentially significant flash
flooding expected.

Discussion...Strong convection continues in a relatively focused
band extending from just northeast of Fayetteville through Branson
currently. This band of convection is tied to a lead mid-level
wave over Missouri that should continue to lift slowly
northeastward and result in subtle subsidence across the
discussion area for at least an hour or two. These trends, along
with slackening low-level flow, suggest that a brief reprieve from
widespread flash flooding (outside of the aforementioned band) in
the short term.

Upstream, mid-level convection was already being agitated in part
due to an approaching mid-level wave evident in satellite imagery
across central Kansas/northern Oklahoma. Additionally, earlier
convection has left behind an outflow boundary across northeastern
Oklahoma and vicinity that connects to a surface low over
north-central Oklahoma. Each of these features (low-level
convergence, mid-level ascent) should result in a redevelopment of
deep convection over the course of the afternoon - though it may
take some time for deeper convection to materialize. The airmass
south of the outflow remains abundantly moist and unstable (2 inch
PW values, 2000+ J/kg MLCAPE). As convection redevelops,
localized training should result in 2+ inch/hr rain rates that
could result in significant flash flooding - especially if the
rainfall occurs in 1) areas that received 2-4 inch rain amounts
earlier today (southwestern Missouri, far northwestern Arkansas),
and 2) across portions of the Arkansas River Valley that have
received 2-8 inches of rain over the past 48 hours.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7rI1I6QlvWvbXX1rE5i0akfkIrAZYFQzvaJwiAevoq_O2ATKzQ99ggbhtq1B15DBKfRB= 9ZYXNadGAfS70RMA7a_sIu4$ for graphic product...

ATTN...WFO...ICT...LZK...OUN...SGF...SHV...TSA...

ATTN...RFC...KRF...ORN...TUA...NWC...

LAT...LON 37969309 37239185 35349188 34269259 34149522=20
34919639 36099646 36809616 37599486=20

=3D =3D =3D
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AWUS01 KWNH 232346
FFGMPD
TNZ000-MSZ000-MOZ000-ARZ000-OKZ000-240415-

Mesoscale Precipitation Discussion 1126
NWS Weather Prediction Center College Park MD
745 PM EDT Tue Sep 23 2025

Areas affected...eastern OK into AR and the MS Valley

Concerning...Heavy rainfall...Flash flooding likely

Valid 232343Z - 240415Z

Summary...Training cells will continue areas of flash flooding
from portions of eastern OK into and across AR to the MS Valley
into the early overnight. Hourly rainfall of 1 to 3 inches and
additional localized totals of 3 to 5 inches are expected.

Discussion...2330Z area radar imagery across the Ozarks into
southeastern OK showed a line of thunderstorms extending ahead of
a cold front in eastern OK, and just north of an outflow-enhanced quasi-stationary front which extended west to east through
north-central AR. Areas of training just south of the Boston
Mountains have been associated with gauge reports of 0.75 to 1.00
inches of rain in 15 minutes and 2+ inches in an hour with ongoing
areas of flash flooding from eastern OK into northwestern AR.

Water vapor imagery showed the leading edge of a shortwave trough
moving east from MO into eastern OK with diffluent flow aloft just
downstream across southern MO and AR. Additional cells, though
isolated, were noted across the 4-state region (MOKSAROK) in
conjunction with the shortwave, with portions of southwestern MO
and northwestern AR having received 72 hour rainfall totals of 2
to 8+ inches (per MRMS estimates). While these cells are moving
into an environment largely worked over, relatively steep lapse
rates could support an isolated core with 1+ inches of rain.
Meanwhile, 850 mb winds ahead of the slow moving cold front were
15-25 kt from the SW, overrunning the outflow/stationary front
across AR with west to east storm motions supporting training. SPC
mesoanalysis data from 23Z indicated plenty of instability with
2000-3000 MLCAPE across eastern OK into western AR along with
PWATs near 2 inches, supportive of high rain rates with this
environment continuing through at least 04Z with minimal CIN.

As the mid-level shortwave continues to advance east, the surface
response will support a slow eastward push to the surface cold
front with cell motions generally toward the east but with
potential for upstream development and continued training
potential. Hourly rainfall of 1 to 3 inches is expected in a few
location along with isolated 3 to 5 inch additional rainfall
maxima through 04Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7lVsWVr0RTiCk-IP4eBt-5wdkDiuGDLA77gMOcfChsNeuepdQzAt3nxeyy7Q2neW3Bil= EfrnvvHpJLxy-wxx2B60Pdg$ for graphic product...

ATTN...WFO...LZK...MEG...SGF...SHV...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 36649429 36569361 35999249 35989145 35638979=20
34868983 34629068 34299182 33959388 34049490=20
34309522 34699543 35189541 35769518 36229468=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 240147
FFGMPD
KSZ000-240730-

Mesoscale Precipitation Discussion 1127
NWS Weather Prediction Center College Park MD
947 PM EDT Tue Sep 23 2025

Areas affected...western KS

Concerning...Heavy rainfall...Flash flooding possible

Valid 240145Z - 240730Z

SUMMARY...Brief training/repeating/backbuilding of showers and
thunderstorms may result in a localized flash flood threat over
portions of western KS over the next several hours. Hourly
rainfall totals of 1 to 2 inches will be possible.

DISCUSSION...GOES East water vapor showed a closed low over
eastern CO/western KS embedded within the base of a sharply
positively tilted longwave trough that extended into the Great
Lakes and eastern Canada. Radar imagery and gauge reports showed
moderate to locally heavy rainfall occurring to the north and east
of a 700-500 mb low along the northern CO/KS border, including a
north-south oriented tail of rain extending toward the south over
western KS. This axis aligned within a low level confluent flow
regime and weak instability (500-1000 J/kg) axis. Mean westerly
winds were found in the deeper layer flow, supporting individual
cell motions toward the east, but the pattern will favor
regeneration of cells within the low level convergence axis over
the next few hours. In addition, left-exit region divergence is
present over the region, tied to a 70-90 kt jet max located from
northern NM into the southern High Plains, which should aid in
vertical ascent over western KS.

The environment will be supportive of 1 to 2 inch hourly totals
due to the potential for brief training/repeating/backbuilding of
cells (slow net movement) but modest moisture (standardized PW
anomalies of +1 to +2) and only weak instability should preclude
higher rainfall rates. Portions of western KS have received well
above average rainfall over the past week (400 to 600+ percent of
normal) with above average soil moisture values leading to a
potentially increased threat flash flood on a localized basis
given low flash flood guidance values of less than 2 inches in 3
hours for portions of the region. The flash flood threat is
expected to slowly translate south as the mid-level trough axis
and low level forcing shift south over the next 6 hours as
forecast by the RAP.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6pIWIJ7BEUMvmUTl6T2nKXh1HPDRkRwTOgoD0ao4ZUMFltBgTntVzK7pQKyLQaJU0Iz0= DdzqJmYp7-_46ubc7euIQ94$ for graphic product...

ATTN...WFO...DDC...GLD...

ATTN...RFC...KRF...TUA...NWC...

LAT...LON 39870121 39830088 39610053 38940006 37539979=20
37140000 37080064 37130099 37320120 37680143=20
38300170 39040181 39500179 39690173 39820159=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 240306
FFGMPD
ARZ000-TXZ000-OKZ000-240900-

Mesoscale Precipitation Discussion 1128
NWS Weather Prediction Center College Park MD
1105 PM EDT Tue Sep 23 2025

Areas affected...Much of Arkansas...Southeast Oklahoma...Far
Northeast Texas...

Concerning...Heavy rainfall...Flash flooding likely

Valid 240310Z - 240900Z

SUMMARY...Developing thunderstorms capable of 1.5-1.75"/hr, likely
to repeat through areas of saturated soils with scattered pockets
of additional 2-4" totals, likely resulting in new incidents of or
continue ongoing flash flooding through the overnight period.

DISCUSSION...GOES-E WV suite depicts broad core of deep upper low
well upstream over the Colorado High Plains dropping southeast;
while a broad elongated mid-level dry slot across centered along
the KS/OK border extending through MO into the Midwest. This has
resulted in a regionally flat mid-level shear axis along and north
of the area of concern. The warm conveyor belt of enhanced deep,
overlapping moisture axis remains very active with large clusters
of cold cirrus shield mainly over SW AR, with only a few
overshooting tops dotting along the moisture axis into far SW
TN/NW MS.

As such, the surface to low level environment remains aligned with
the warm conveyor. A weak surface to 850mb low is exiting NE OK
into the Ozark Plateau, with upstream cold advection occurring
across E OK. This sharpening has increased convergence along a
remaining axis of 2000 J/kg of MLCAPE supporting a secondary
increase in convective vigor and coverage upstream of the initial
band that is slowly eroding and becoming more scattered in nature
across central AR toward the TN/MS line. With additional
development upstream of areas already flooded across NW AR and E
OK, additional 2-3" totals due to 1.5"/hr rates is likely to
maintain ongoing flooding situations.

However, further southwest, the reservoir of remaining
unstable/unmixed air across the Red River Valley has a bit broader
instability axis to work with and thunderstorms are just that bit
stronger with tops below -70C. 500-1000mb thickness depicts a
broadening divergence suggesting weakening propagation vectors,
slowly backing upstream to suggest some back-building may occur
over the coming hours. This clustering/expansion will increase
mergers, short-term training across far SE OK/SW AR into far
northern TX. Slightly higher moisture flux convergence will also
support rates of 1.75"/hr, occasionally and locally peaking over
2"/hr. As such spots of 2-4" are becoming more likely. The area
has not seen the heavier rain over the last week or so, as further
north, so grounds are a bit more accepting of these higher totals;
given FFG values of 2-3"/hr or 3-4"/3hrs, suggesting incidents of
flash flooding will still be more scattered in nature/coverage
than further north, but a few incidents are still likely (with the
only exception near Montague to Grayson county, TX).

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!44jtdujgBJ1BR-OWzjRm12Isx_zZyOiDd0-tIodVhFT_r9EPUHV_w59ZlRPmW7XyDPW3= j0Q9impEEnprN8J13F1okbo$ for graphic product...

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

ATTN...RFC...FWR...ORN...TUA...NWC...

LAT...LON 36099332 35609171 34979117 34089141 33419292=20
33149393 33009526 33099734 33709764 34529643=20
35339522 36079432=20

=3D =3D =3D
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AWUS01 KWNH 240842
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-241415-

Mesoscale Precipitation Discussion 1129
NWS Weather Prediction Center College Park MD
441 AM EDT Wed Sep 24 2025

Areas affected...Southern AR...Northern LA...Far Western MS...Ext
Southeast OK...Ext Northeast TX...

Concerning...Heavy rainfall...Flash flooding possible

Valid 240840Z - 241415Z

SUMMARY...Strong moisture flux and rates over 2"/hr with
short-term training poses streaks of 2-4" totals and possible
incidents of flash flooding through early morning.

DISCUSSION...Regional RADAR mosaic continues to show stronger
clusters of thunderstorms extending west to east along older
convectively reinforced boundaries across central to southern AR
and into NW MS. Broad southwesterly LLJ continues to flux
enhanced lower level anomalous moisture to intersect with the
boundary to maintain isentropic ascent, to tap skinny but still
unstable profiles with 2000-2500 J/kg of CAPE. The southwesterly
flux combined with very slow southward drift of the boundary has
allowed for overall moisture profile to reach 2-2.25" total PWat
values and raise warm cloud layers a few extra thousand feet,
increasingly efficient warm cloud rainfall generation, supporting
rates of 2-2.5"/hr.=20

GOES-E WV suite shows base of the main core, upper-low continuing
to advance across the TX Panhandle, this has delayed the
advancement of the cold front across eastern OK, further allowing
the length of the isentropic ascent to be long enough to allow for repeating/training for those scattered clusters. LLJ winds are
expected to increase to 25-30kts but also veer a bit more to
reduce angle of intersection with the effective isentropic
boundary toward daybreak and may further reduce overall coverage.
Still, the deep layer steering flow will be just a bit south of
due east allowing for short-term training/repeating to remain
across southern Arkansas and far Northern Louisiana and perhaps
into far western MS after 12z. Streaks of 2-4" are possible but
this will also be crossing areas that have been dry for a
prolonged period and higher FFG values in general.

NASA SPoRT LIS 0-40cm relative soil moisture values are generally
below 30% with some as low as 10% in main river valleys. Intense
rates initially up to 2.5"/hr may not have much time to infiltrate
and could have above normal run off, so any flash flooding
incidents are likely to be more widely scattered in nature and
therefore the risk is considered possible through 14z.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-fBZGZfQ8KmwaZf1e3ZpdkCGVGFkwPwh4oASsTypnjtvIng4Z5YvxODWCTZ66vXGtinp= -ltHPoal8_P6C_DTFXjT89I$ for graphic product...

ATTN...WFO...JAN...LZK...SHV...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON 34589183 34159116 33239042 32699067 32609141=20
32609301 32999465 33659507 34059491 34409418=20
34289297=20

=3D =3D =3D
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AWUS01 KWNH 241348
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-241900-

Mesoscale Precipitation Discussion 1130
NWS Weather Prediction Center College Park MD
948 AM EDT Wed Sep 24 2025

Areas affected...Eastern Texas through far Western Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 241347Z - 241900Z

Summary...Clusters of showers and thunderstorms will continue into
the afternoon as a cold front approaches from the Northwest. This
convection will likely have rain rates of 2-3"/hr, which through
training or repeating could produce 2-4" of rain and instances of
flash flooding.

Discussion...The regional radar mosaic this morning shows clusters
of thunderstorms advancing across portions of Louisiana, Arkansas,
and eastern Texas. These thunderstorms are developing ahead of a
cold front analyzed by WPC moving across Texas, with outflow
boundaries from prior thunderstorms driving additional ascent.
Synoptically, deep layer ascent is also intensifying across the
region as a longwave trough digs slowly across Oklahoma driving
height falls, while a jet streak arcs from the Southern Plains
into the Appalachians, providing favorable diffluence within the
RRQ. Additionally, a wave of low pressure moving along the cold
front is resulting in locally accelerated 850mb winds measured to
25-35 kts, providing not only enhanced convergence, but driving
more impressive moisture northeast into the region.

Thermodynamics remain impressive as well. PWs as measured by GPS
and morning 12Z U/A soundings are around 2 inches, above the 90th
percentile from the SPC sounding climatology, which is overlapped
with MUCAPE as much as 3000 J/kg. The impressive ascent into these
robust thermodynamics is producing rainfall rates that are
estimated via local radars to be more than 2.5"/hr, resulting in
MRMS 1-hr rainfall that has been as high as 2-3" across parts of
AR.

As the morning progresses, the slow translation east of the cold
front and accompanying wave of low pressure into the favorable
environment should result in an expansion and intensification of
convection, especially from eastern TX into the ArkLaTex region.
Although the CAMs differ highly in their evolution and rainfall
footprint, recent convective development across eastern TX
suggests that activity will ramp up again, and both the HREF
neighborhood probabilities and the HRRR 15-min rainfall
accumulations indicate rates will surge at times to 2-3"/hr,
locally and briefly up to 4"/hr.

With 0-6km mean winds aligned to the front, and Corfidi vectors
becoming increasingly anti-parallel to this mean wind, at least
short term training is likely the next several hours. Although
recent rainfall has been modest which is reflected by anomalously
dry soils according to NASA SPoRT, any significant training of
these intense rates could result in instances of flash flooding
the next several hours.


Weiss

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!572e6vx4cbw-JQokAdKt_aOfli4n5MxOU8P-IqRKdBxKoPTfdOp9zBRhBSWovxtJ4UBG= o3Vq8fOUoN2_HrwVI4pCkGo$ for graphic product...

ATTN...WFO...FWD...HGX...JAN...LZK...MEG...SHV...

ATTN...RFC...FWR...ORN...TUA...NWC...

LAT...LON 34549143 33539057 32979068 32539137 32119234=20
31769341 31209480 30829545 30719646 31179695=20
31879662 32909532 34369316=20

=3D =3D =3D
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AWUS01 KWNH 241740
FFGMPD
MSZ000-LAZ000-TXZ000-242300-

Mesoscale Precipitation Discussion 1131
NWS Weather Prediction Center College Park MD
140 PM EDT Wed Sep 24 2025

Areas affected...Middle Texas Coast through southern Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 241739Z - 242300Z

Summary...Showers and thunderstorms will continue to expand across
the Central Gulf Coast this aftn. Rainfall rates will likely reach
2-3+"/hr at times, leading to stripes of 2-4" of rainfall. This
may cause flash flooding.

Discussion...The regional radar mosaic early this aftn shows
rapidly expanding coverage of reflectivity associated with
increasing showers and thunderstorms from the Middle Texas Coast
through southern Mississippi. This activity is blossoming
downstream of a cold front that is slowly dropping southeast,
driven by an elongated longwave trough axis diving through the
Southern Plains. This evolution is driving subsequent downstream
jet streak formation, leading to favorable RRQ diffluence aloft.
Additionally, spokes of shortwave energy rotating through the
trough axis are providing additionally focused ascent.

This widespread deep layer lift is impinging into a destabilizing
environment reflected by recent SPC RAP analyzed SBCAPE of
2500-3500 J/kg. This instability is combining with impressive
moisture (PWs of 2-2.2 inches as measured by GPS) to produce an
environment ripe for heavy rainfall production. This is being
realized by the expansion of convection, and recent
radar-estimated rain rates have peaked above 1.5"/hr, despite
current cells featuring relatively small updrafts with short
temporal lifespans (pulse variety convection).

As the aftn progresses, the high-res guidance is in good agreement
that thunderstorm coverage will expand across most of the area,
and recent HRRR runs have shown an increasing trend in coverage.
This is likely supported by the more favorable overlap of ascent
into the rich thermodynamic airmass this aftn, as the trough and
accompanying cold front continue to expand southward.
Thunderstorms that develop will also be supported by increasing
bulk shear to help organize into clusters. This should have the
dual-pronged effect of creating heavier rain rates (HREF
neighborhood probabilities peak around 40% for 2"/hr coincident
with 15-min HRRR rainfall as much as 1", or brief 4"/hr rates)
while also leading to longer duration of this rainfall.
Additionally, with 850mb inflow remaining out of the Gulf to
resupply favorable thermodynamics, propagation vectors collapse to
around 5 kts and veer more to the north, indicating that storms
will be slower moving and may build south along the TX coast.

Where clusters of storms move slowest or backbuild/train, these
intense rainfall rates could produce 2-4" of rain (HREF 6-hr
rainfall probabilities for 3" above 40%). This will be sufficient
to produce rapid runoff even atop the relatively dry antecedent
soils. While the greatest threat for impacts will occur where
heavy rain falls atop urban areas, any training or repeating of
these rain rates across this area could result in instances of
flash flooding into this evening.


Weiss

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_zRYIjj0FnOKPOPdWsofhDiO5Tk0fu2rbnBSPvxZt-6moVXQLnEfhWe4TkXBjQZbacQj= VgeYiIcPKq64JIi0A94N8rg$ for graphic product...

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

ATTN...RFC...FWR...ORN...NWC...

LAT...LON 33139065 33088902 32388871 31468919 30378971=20
30008992 29769040 29679116 29749201 29869315=20
29709382 29489434 29239489 29029541 28909600=20
29089656 29699573 30179528 30739486 31499392=20
32729179=20

=3D =3D =3D
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AWUS01 KWNH 242025
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-250130-

Mesoscale Precipitation Discussion 1132
NWS Weather Prediction Center College Park MD
425 PM EDT Wed Sep 24 2025

Areas affected...lower to mid-MS Valley into northwestern TN and
KY

Concerning...Heavy rainfall...Flash flooding possible

Valid 242023Z - 250130Z

Summary...At least an isolated flash flood threat will evolve
through this evening from the lower/middle MS Valley into
northwestern TN and KY. Hourly rainfall of 1 to 2 inches and
localized totals of 2 to 4 inches are expected through 01Z.

Discussion...Radar trends over the past hour have shown an
increase in the coverage of showers and thunderstorms from
northeastern AR into southeastern MO and western KY. These storms
were forming along a quasi-stationary front and just ahead of a
positively tilted mid to upper-level trough axis located over
IL/MO into northeastern OK as observed on water vapor imagery.
Filtered sunshine and anomalous PWAT values of 1.5 to 2.0 inches
have contributed to MLCAPE of 500 to 1000+ J/kg via 20Z SPC
mesoanalysis data.

850 mb winds of 20 to 30 kt were observed across the lower MS
Valley into northern MS/southwestern TN via VAD wind data, just
ahead of the base of the mid-level trough. As the trough axis
advances eastward through the evening, the region of locally
stronger low level winds are forecast by the RAP to expand
northeastward into TN/KY, aiding with axes of low level
convergence (in addition to the surface front and resultant
outflows). This will occur beneath a divergent pattern aloft
within the right-entrance region of a 110-130 kt jet at 250 mb
expanding northeastward from MO/IL. The result should be an
increase in thunderstorm coverage, especially over the
lower/middle MS Valley with areas of training from SW to NE.
Within axes of training, hourly rainfall of 1-2 inches will be
likely with potential areas of flash flooding from 2 to 4 inches
of storm total rainfall through 01Z to 02Z. Given somewhat meager
instability and low level winds into KY/TN, the response is not
expected to be well organized or widespread with any instances of
flash flooding most likely remaining isolated to widely scattered.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9P6K1YSV1g-oYcsPKuRKvFlzLvYcIb1lOcX1ZD2dHC2KZTFTB8T6nspZU7uxLQV6Q9Ts= fKocw4fFrIkTggaDdrCiav0$ for graphic product...

ATTN...WFO...JKL...LMK...LZK...MEG...OHX...PAH...SGF...

ATTN...RFC...MSR...ORN...TIR...NWC...

LAT...LON 38178393 37948310 37498279 37148314 36848430=20
36318687 35898854 35299000 35149152 35749202=20
36899120 37788852 38108581=20

=3D =3D =3D
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AWUS01 KWNH 250128
FFGMPD
WVZ000-OHZ000-TNZ000-KYZ000-INZ000-ILZ000-MOZ000-250700-

Mesoscale Precipitation Discussion 1133
NWS Weather Prediction Center College Park MD
927 PM EDT Wed Sep 24 2025

Areas affected...far northwestern TN into most of KY to the OH
River

Concerning...Heavy rainfall...Flash flooding possible

Valid 250127Z - 250700Z

Summary...Localized flash flooding may continue across far
northwestern TN into most of KY to the OH River through 07Z.
Periods of training/slow net movement of heavy rain cores will
support hourly totals of 1 to 2+ inches and possible isolated
totals of 2 to 4 inches.

Discussion...Regional radar imagery at 01Z showed scattered
showers and embedded thunderstorms extending from southeastern MO
into northwestern TN and western/central KY, near a
quasi-stationary front which was analyzed near the OH River. A
number of smaller scale mesovortices were noted within this axis,
one just west of I-65 in central KY and another over southern KY
to the southwest of HVC. While overall instability was generally
weak across the OH Valley, with 00Z soundings from ILN and BNA
showing less than 250 J/kg MLCAPE, pockets of higher instability
(though still weak) likely remained over portions of TN/KY. One of
the bigger drivers in a lingering flash flood threat is the
anomalous moisture in place with PWAT values between 1.6 and 2.0
inches (00Z BNA sounding and SPC mesoanalysis), supportive of
efficient rainfall production with MRMS-derived rates of 1 to 2
in/hr (locally higher) since 22Z.

Forcing ahead of a slow moving mid-level trough/low over MO and
associated shortwave trough will continue to support showers and
thunderstorms through a good portion of the overnight for the OH
Valley. As the shortwave spoke over MO advances eastward into the
OH Valley through 12Z areas of heavy rain will clear from west to
east. Embedded pockets of heavy rain are expected within lingering
elevated instability pools and/or near transient mesovortices,
with lift being augmented through divergence and diffluence aloft
within the right-entrance region of an upper jet max currently
over IN/OH. Within axes of training, hourly rainfall will continue
to peak in the 1 to 2 inch range (locally higher possible) along
with additional storm totals of 2 to 4 inches through 07Z.
Localized flash flooding may result, especially if there is
overlap with urban areas.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7iG0BeSVrc8-e8U2NIiwia8yQ1ZpFR7PuWCUkyHAp5UPY2t8HzoFNl9e48hQO_6Qpx-T= YaSnQxf9400Q2L7JM9sTT8A$ for graphic product...

ATTN...WFO...ILN...JKL...LMK...MEG...OHX...PAH...RLX...

ATTN...RFC...ORN...TIR...NWC...

LAT...LON 39038267 38678217 38078287 37148386 36618525=20
36298684 36098851 36078929 36418952 37188883=20
38048683 38848449=20

=3D =3D =3D
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AWUS01 KWNH 250716
FFGMPD
PAZ000-MDZ000-WVZ000-OHZ000-KYZ000-251300-

Mesoscale Precipitation Discussion 1134
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Sep 25 2025

Areas affected...portions of northern KY/WV...southern
OH...southwestern PA

Concerning...Heavy rainfall...Flash flooding likely

Valid 250715Z - 251300Z

Summary...Localized hourly 1-2" rainfall expected to result in
additional 2-4" totals, in the vicinity of recent localized 1-3"
rainfall over the past few hours. Isolated to scattered instances
of flash flooding are likely.

Discussion...Showers with embedded thunderstorms have continued in
the vicinity of a quasi-stationary front draped from southwest to
northeast across the OH Valley. A deepening (but weak) wave of low
pressure along the front is approaching an area of recent
localized training (1-2" estimated hourly totals per MRMS) near
the far eastern OH/KY border, fueled by a trailing mid- to
upper-level shortwave/PV anomaly (evident via GOES-East water
vapor imagery and 500 mb RAP analysis). The leading edge of
moisture transport situated between 300-305K isentropes (~850 mb
isobaric surface) is only just moving into the OH/KY/WV border
region, as the low-level jet nears peak strength at 30-40 kts.
This suggests that embedded hourly 1-2" totals will likely
continue for at least the next several hours, training near recent
1-3" totals in already sensitive hilly to mountainous terrain
(with 3-hr FFGs, Flash Flood Guidance, generally ranging from only
1.0-2.0"). Recent hi-res guidance supports the idea of additional
localized 2-4" totals, suggesting isolated to scattered instances
of flash flooding are likely.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5Aw_vEfG7FFGaSxd4hr9Wq9tNCJL1Mwli-GymTVjIsxs7osraLU9emLxSXg275LTpFAb= QJ-LnTPJVZrT6mUY1I_cXeA$ for graphic product...

ATTN...WFO...ILN...JKL...LMK...PBZ...RLX...

ATTN...RFC...TIR...NWC...

LAT...LON 40898023 39507946 38588062 38038300 38158379=20
38498393 38778366 39178306 39788228=20

=3D =3D =3D
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AWUS01 KWNH 251303
FFGMPD
PAZ000-WVZ000-OHZ000-251702-

Mesoscale Precipitation Discussion 1135
NWS Weather Prediction Center College Park MD
903 AM EDT Thu Sep 25 2025

Areas affected...western/central Pennsylvania, far southeastern
Ohio

Concerning...Heavy rainfall...Flash flooding possible

Valid 251302Z - 251702Z

Summary...Deep convection should migrate eastward across western
and central Pennsylvania this morning, producing areas of 1-2
inches of rainfall (locally higher). These amounts may cause
flash flooding especially in populated and sensitive areas.

Discussion...Deep convection was being maintained across
southeastern Ohio this morning due to strong forcing for ascent
aloft with mid-level waves traversing the region. Latest MRMS
estimated of 1-2 inch/hr rain rates were noted particularly with a
cluster of cells near Wheeling, WV. These cells were moving
eastward at an appreciable clip, but were still embedded in just
enough instability aloft (around 250 J/kg MUCAPE) and abundant
moisture (1.8 inch PW) to support heavy rainfall. These cells
should impact the Pittsburgh Metro area over the next couple
hours, and if rain rates persist as they are currently, at least a
few instances of flash flooding are possible.

Over time, convection is expected to continue spreading eastward,
with multiple rounds of rain rates of at least 0.25-0.5 inch/hr
expected. Localized areas of hourly rates exceeding 1 inch/hr are
also possible at times. FFG thresholds are in the 1-1.25 inch/hr
range and exceedence is likely on at least an isolated basis.=20
Flash flooding is possible in this regime - particularly in
low-lying and urbanized areas.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4hE2zsVbw4s659OivZb8zifpnq8tFG3kLmqkaiCb0qaria4T--OhaUzjYU26t5vMcKW4= 9TCQhHGnBgeEdJsI3evHzAo$ for graphic product...

ATTN...WFO...CLE...CTP...PBZ...RLX...

ATTN...RFC...RHA...TIR...NWC...

LAT...LON 41577859 40907814 39897891 39338143 40858150=20
41258051=20

=3D =3D =3D
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AWUS01 KWNH 251856
FFGMPD
MEZ000-MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-NJZ000-PAZ000-260050-

Mesoscale Precipitation Discussion 1136
NWS Weather Prediction Center College Park MD
255 PM EDT Thu Sep 25 2025

Areas affected...northern Mid-Atlantic into southern New England

Concerning...Heavy rainfall...Flash flooding possible

Valid 251854Z - 260050Z

Summary...Training axes of heavy rain are expected from the
northern Mid-Atlantic region into southern New England through the
late afternoon and evening. Hourly rainfall of 1 to 2+ inches may
result in localized flash flooding with a focus on any urban
centers.

Discussion...Radar imagery at 1845Z helped identify a pair of MCVs
over the Northeast, embedded within areas of largely stratiform
rain from portions of PA into New England. One vortex over central
PA and the other near Albany, NY, were tied to surges of higher
rainfall rates, with MRMS-derived values between 1 and 2 inches in
an hour at times. These two features were located along the
northern edges of a region of elevated CAPE with 500-1500 MUCAPE
identified on 18Z SPC mesoanalysis data. The environment was
characterized by anomalous moisture with PW values of roughly 1.7
to 2.0 inches (2 to 3 standardized anomalies above the mean for
late September), supportive of hourly rainfall locally in excess
of 2 inches.

As a cold front over central NY/PA and the aforementioned
mesoscale waves continue to advance downstream, interaction with
500-1000 J/kg MLCAPE from southeastern PA into far southern New
England will support an increase in rainfall coverage and rates
from the northern Mid-Atlantic into southern New England. Some
breaks in cloud cover noted on visible imagery over southeastern
PA into NJ may help to locally increase instability through better
surface heating, yielding greater potential for higher intensity
rainfall. While individual cell motions should remain progressive
toward the NE, alignment of convective axes with the southwesterly
deep-layered steering flow will promote training and locally 1 to
2+ inches of rain in an hour at times. These locally higher rates
could result in a relatively quick accumulation of rainfall
totaling 2 to 3+ inches through 01Z. Localized flash flooding may
occur as a result, especially if overlap occurs with impervious
urban areas.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7qyxmCwKpVstv3jN3fWwdyMQipUMRXzIhAqbmAEL2oR2LO2905s5-kjeFo6cNeEXp8M6= 6v4dkwIDL3tkbvHKIqKkVYQ$ for graphic product...

ATTN...WFO...ALY...BGM...BOX...BTV...CTP...GYX...OKX...PHI...

ATTN...RFC...RHA...TAR...NWC...

LAT...LON 44247137 43667053 43137030 42647034 42237087=20
41847183 41297270 40817343 40227422 39927557=20
39917773 40897709 42027600 42747491 43117379=20
43807248=20

=3D =3D =3D
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AWUS01 KWNH 251942
FFGMPD
NMZ000-AZZ000-260130-

Mesoscale Precipitation Discussion 1137
NWS Weather Prediction Center College Park MD
340 PM EDT Thu Sep 25 2025

Areas affected...central to southeastern AZ into southwestern NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 251939Z - 260130Z

Summary...Scattered thunderstorms are expected to result in a few
areas of flash flooding from central and southeastern AZ into
southwestern NM through early evening. Rainfall rates of 1-2 in/hr
will be likely within the stronger cores.

Discussion...Visible satellite and area radar imagery showed the
rapid development of thunderstorms over north-central to
southeastern AZ over the past hour. The storms overlapped within
an anomalous low to mid-level moisture axis seen on LPW imagery,
located east of a dry tongue which existed over southern CA into
southern NV. Favorable surface heating beneath mostly clear skies
and the anomalous PW axis (+1 to +2 standardized anomalies) have
led to 500-1500 J/kg MLCAPE via 19Z SPC mesoanalysis data (~1100
J/kg via 18Z TUS sounding) over a large portion of the MPD area.

Steering flow varied across the region but was oriented from the
SSW to W and was stronger across northern regions compared to
locations closer to the Mexican border. Mid-level height falls and
upper level left-exit region jet max divergence, at the nose of a
zonally oriented jet streak moving into northern Baja California,
should aid in lift across the region later this afternoon. The
environment will support scattered thunderstorms increasing
through the evening with brief training and outflow interactions
as storm coverage increases. 1 to 2 inches of rain in an hour (or
less) should be found within the stronger thunderstorm cores that
develop and is expected to result in at least isolated flash
flooding into the early evening.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6oje_8QJMjjKuArnunfaQn1FApIpa7M3iTh5gDWrUxTJgXgoaqCgwwYgFIHmazke7Q4g= mTqL1XAh1CmatsvDW4Cto_Y$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 35441210 35141068 34260919 33150779 32580722=20
31660702 31120790 31090952 31261079 31661115=20
32671115 33991164 35131245=20

=3D =3D =3D
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AWUS01 KWNH 252025
FFGMPD
NVZ000-CAZ000-260215-

Mesoscale Precipitation Discussion 1138
NWS Weather Prediction Center College Park MD
424 PM EDT Thu Sep 25 2025

Areas affected...Sierra Nevada into portions of central NV

Concerning...Heavy rainfall...Flash flooding likely

Valid 252023Z - 260215Z

SUMMARY...Intense heavy rain cores are expected to result in at
least isolated flash flooding into the afternoon and early evening
hours from the Sierra Nevada into portions of central NV. Hourly
rainfall of 1 to 2 inches is expected but with sub-hourly totals
of 0.5 to 1.0 inches in 15-30 minutes.

DISCUSSION...GOES West visible satellite imagery and ENTLN
lightning data showed a few widely scattered thunderstorms from
the Sierra Nevada into portions of south-central NV. The storms
were located to the north and east of the 700 mb reflection of a
mid-level low over CA, with highly anomalous moisture (2 to 3+
standardize PW anomalies) extending from the low center into much
of NV. VAD wind data at 700 mb and RAP guidance showed 20-30 kt
wind speeds at 700 mb over the lower CO River Valley into southern
NV but weakening to ~10 kt over central and western NV (some
degree of speed convergence).

Deeper layer mean wind speeds were weak (<10 kt) under and north
of the mid-level low which will result in slow cell motions.
Placement of the mid-level low to the west of the Sierra Nevada
and southerly flow to its east, aligned with the orientation of
the Sierra Nevada range will likely result in some repeating
rounds of thunderstorms across the higher terrain where 500-1000
J/kg of instability is forecast to expand by later this afternoon.
Farther to the east, from western to central NV, favorable
unidirectional southerly flow will increase the potential for
training and brief backbuilding of cells where locally stronger
low level flow exists. Due to the anomalous moisture in place,
both areas of CA and NV will have the potential for high rainfall
rates, hourly totals of 1 to 2 inches and 0.5 to 1.0 inches in
15-30 minutes, which should result in at least isolated areas of
flash flooding into the evening hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_nZGtwH_GXyul5EIDi8z1LU22llk81oAmhDmVrjBphJ_-ppZR8Z6Gytx8F2BTSt-WyXv= EPAlC_RBSuEqhOHi3m7piPQ$ for graphic product...

ATTN...WFO...HNX...LKN...REV...STO...VEF...

ATTN...RFC...RSA...NWC...

LAT...LON 39871830 39761745 39141638 37841613 37041697=20
36121781 35801851 35881877 36341898 36751920=20
37171968 37512003 37962031 38332050 38912031=20
39431975 39761896=20

=3D =3D =3D
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AWUS01 KWNH 261604
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-262130-

Mesoscale Precipitation Discussion 1139
NWS Weather Prediction Center College Park MD
1203 PM EDT Fri Sep 26 2025

Areas affected...Far Southeast NV...Northwest to Central AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 261603Z - 262130Z

SUMMARY...Increasing coverage of heavy showers and thunderstorms
can be expected over the next few hours. Slow cell-motions and
localized backbuilding of convective cells will promote sufficient
rainfall concerns for isolated to scattered areas of flash
flooding to be possible going through mid-afternoon.

DISCUSSION...The latest GOES-W IR/WV suite shows a compact and
relatively strong mid to upper-level low center dropping
east-southeastward down across southeast CA. Left-exit region jet
dynamics pivoting up across central to northwest AZ around the
eastern flank of this closed low is already interacting with a
nose of moderate instability pooling around the southwest-facing
slopes of the Mogollon Rim and adjacent areas of central AZ. The
result over the last couple of hours has been a corridor of
cooling convective tops, with radar data showing pockets of
backbuilding convective cells near and over top of the higher
terrain.

SBCAPE values are locally on the order of 1000 to 2000 J/kg, and
additional boundary layer destabilization via solar insolation
over the next few hours will contribute to an additional uptick in
convective coverage with showers and thunderstorms becoming a bit
more focused over the Mogollon Rim and adjacent areas just to the
south over central AZ. A well established corridor of strong
850/700 mb moisture flux anomalies are aligned with the deeper
layer south-southwest flow riding up across southern and central
AZ to the east of the closed low center, with these anomalies
reaching 2 to 3 standard deviations above normal. This will
facilitate the expansion of convection along with a favorable
regime for backbuilding cells.

Farther off to the northwest across northwest AZ and adjacent
areas of far southeast NV, convection will be developing here over
the next few hours as a mid-level deformation zone north of the
closed low becomes better established. A destabilizing boundary
layer coupled with terrain-influenced circulations will help
further support convective development.

Rainfall rates with the convection across the region will be
capable of reaching 1 to 1.5 inches/hour with the stronger cells,
and with slow cell-motions and some backbuilding cells, there may
be some storm totals through mid-afternoon that region 2 to 2.5
inches. This is consistent with the latest 12Z HREF guidance.

Given the setup, isolated to scattered areas of flash flooding
will be possible, and this threat is expected to continue
throughout much of the day. Additional MPDs will be issued
accordingly.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-DbPkAA0-R7L4BdeFk7FxNiGA5fR2J9USSaEG5r6qM0kzQ9t5yJ7n9cbhrEPBD3-VyZ3= nKcv1yFZLaWba0vs0qqLKOs$ for graphic product...

ATTN...WFO...FGZ...PSR...SLC...TWC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 37241454 37071344 36491210 35751003 34670911=20
33730917 33100985 32991121 33431260 34501353=20
34901453 35621545 36331577 36971536=20

=3D =3D =3D
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AWUS01 KWNH 261847
FFGMPD
NMZ000-AZZ000-270045-

Mesoscale Precipitation Discussion 1140
NWS Weather Prediction Center College Park MD
245 PM EDT Fri Sep 26 2025

Areas affected...Central to Southeast AZ...Southwest NM

Concerning...Heavy rainfall...Flash flooding likely

Valid 261845Z - 270045Z

SUMMARY...Expanding clusters of heavy showers and thunderstorms
this afternoon will likely drive scattered to numerous areas of
flash flooding. Locally significant and life-threatening impacts
will be possible.

DISCUSSION...The latest GOES-W visible satellite imagery along
with radar data shows expanding clusters of heavy showers and
thunderstorms across central AZ to the southwest of the Mogollon
Rim and to the north of Phoenix, with additional areas of
convection also seen developing off to the east and southeast
across southeast AZ. All of this convection is developing and
expanding in coverage in response to the arrival of a compact
closed low over southeast CA which is allowing for notably
divergent flow aloft downstream across central and southern AZ
while also interacting with a strongly unstable and moist boundary
layer.

MLCAPE values are on the order of 1500 to 2500 J/kg with 850/700mb
moisture flux anomalies of 2 to 3 standard deviations above normal
across the region ahead of the approaching height falls. As
additional boundary layer heating ensues across the region, there
will likely be additional expansion of convection which is
expected to become locally quite concentrated across portions of
central to southeast AZ. In time this afternoon, convection is
also expected to develop farther off to the east into areas of
southwest NM, which will have the aid of orographic ascent and
differential heating boundaries to support convective development.

Rainfall rates will be capable of reaching 1 to 2 inches/hour with
the stronger storms, and the environment is highly conducive for
pockets of slow-moving cells and backbuilding convection. This may
support some rainfall totals reaching 2 to 4 inches by late this
afternoon. This is generally supported by the latest HREF/REFS
guidance suites.

Given the coverage and intensity of the convection that is
expected to unfold this afternoon, scattered to numerous areas of
flash flooding are expected. This will include concerns for
enhanced dry wash/arroyo flash flooding along with potential for
areal burn scar impacts. Urban flash flooding will also be a
possibility including locations such as Phoenix, Tuscon and
Safford. Thus, locally significant and life-threatening impacts
will be possible where these heavier rains materialize over the
next several hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6ZnUcNqjMcMtxd7B7uzBHV7R59cx426Q6EmeUoLpra_febM6hg8lxqJq-jhapBGmxJwk= H6m270gD4kLpom0IjSTkYpQ$ for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 35021202 34541068 34470938 34600731 33260674=20
31730756 31150855 31020977 31131108 31611178=20
32301208 33061239 34221308 34871279=20

=3D =3D =3D
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AWUS01 KWNH 262131
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-270330-

Mesoscale Precipitation Discussion 1141
NWS Weather Prediction Center College Park MD
530 PM EDT Fri Sep 26 2025

Areas affected...Eastern CA...Southeast NV...Southwest
UT...Northwest AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 262130Z - 270330Z

SUMMARY...Heavy showers and thunderstorms will be a threat going
into the evening hours across portions of eastern CA, southeast
NV, southwest UT and northwest AZ. Additional isolated to
scattered areas of flash flooding will be possible.

DISCUSSION...The latest GOES-W IR satellite imagery shows
cold-topped convective clusters impacting northwest AZ along with
southwest UT. Radar imagery shows this activity gradually
beginning to cyclonically advance westward into portions of far
southern NV and with some cells attempting to develop over far
eastern CA. The convection across this region is largely focused
within a well-defined mid-level deformation zone situated north of
a closed mid to upper-level low center across eastern CA.

A corridor of focused moisture convergence is seen wrapping up
around the eastern and northern flanks of the closed low, and
there is an axis of MLCAPE values reaching 500 to 1000 J/kg nosing
up through northwest AZ and into far southeast NV. This coupled
with deep layer ascent/forcing north of the closed low should help
maintain a threat for convection going into the evening hours.
Overall, far northwest AZ should tend to see the greatest threat
over the next few hours, but areas of southern NV and eastern CA
will likely see more development of showers and thunderstorms
given close proximity of the closed low. This is consistent with
the latest runs of the experimental WoFS guidance.

The moisture environment is relatively moist with PW anomalies of
1 to 2 standard deviations above normal. This coupled with the
larger scale ascent and instability should maintain convective
cells capable of producing rainfall rates of 1 to 1.5 inches/hour.
Additional rainfall totals locally of up to 2 inches will be
possible by late this evening where some of these cells tend to be
slow-moving or anchored near terrain.

Additional isolated to scattered areas of flash flooding will be
possible as a result going through this evening. This will include
potential impacts to any burn scar locations along with the
normally sensitive slot canyons and dry washes.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6A3ai2NIo4VpwyFwvySxD1vFN7nCkXNx8SpimzhhlzabtE4BIOz_C1KTNaaP9Dhprq2i= tLqM40gfidN9QyRZN_GFx2Q$ for graphic product...

ATTN...WFO...FGZ...PSR...SLC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 37911254 37681175 36991175 36001260 35181288=20
34451317 33511359 33171437 33251529 33811597=20
34971616 35791604 36511573 37231505 37741396=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 262348
FFGMPD
VAZ000-NCZ000-TNZ000-270545-

Mesoscale Precipitation Discussion 1142
NWS Weather Prediction Center College Park MD
747 PM EDT Fri Sep 26 2025

Areas affected...Western NC...Southwest to South-Central VA

Concerning...Heavy rainfall...Flash flooding possible

Valid 262347Z - 270545Z

SUMMARY...Slow-moving showers and thunderstorms may become a bit
more focused going into the overnight hours. High rainfall rates
and slow cell-motions may result in isolated to scattered areas of
flash flooding.

DISCUSSION...An upper-level trough gradually advancing into the
Southeast U.S. will be interacting with a moist and unstable
airmass this evening pooling up along a quasi-stationary front
situated across the eastern slopes of the southern Appalachians
and southern portions of the Mid-Atlantic region. Surface
observations show a wave of low pressure developing along this
boundary over southwest NC which is gradually lifting off to the
northeast.

This surface wave is being facilitated by the gradual
amplification of height falls across the region which is promoting
a southwest to northeast axis of right-entrance region upper jet
dynamics and related deep layer ascent. MLCAPE values of 500 to
1000 J/kg are pooled ahead of this wave along the front across
western NC and some uptick in low-level moisture convergence into
the boundary is expected over the next several hours.

An increase in the concentration of convection along the front is
expected across western NC and eventually parts of southwest to
south-central VA going into the overnight hours as stronger upper
jet forcing and strengthening frontogenesis takes place. The
pooling of moisture and at least modest instability will be
maintained as well, and some of the convection will be capable of
producing high rainfall rates of 1 to 2 inches/hour.

The higher rates will be supported by a gradual increase in PWs
which are already near 1.5 inches, and with increasing potential
for warm rain processes to take place going into the overnight
hours. Moderate effective bulk shear of 30 to 40 kts will also
promote at least some loosely organized convective cells in close
proximity to the front which will further support elevated
rainfall rates.

Hires model CAMs going through 06Z/2AM EDT suggest rainfall totals
of as much as 2 to 4+ inches at least locally. This may support
isolated to scattered areas of flash flooding, and especially
across portions of northwest NC into southwest VA where antecedent
conditions are relatively moist.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!90yAwvX8v-WxaAj_C9qZbPnkJLnBAfhujoJAb7j5KfiJ5UvQkRcyMaZ4cCycFfxsHg8N= Nda4MXSitxhU-0zc5cUhogs$ for graphic product...

ATTN...WFO...AKQ...GSP...MRX...RAH...RNK...

ATTN...RFC...ALR...ORN...RHA...TIR...NWC...

LAT...LON 37407935 37367865 36957807 36447834 35917948=20
35538017 35308069 35298131 35588190 36138199=20
36898105 37308008=20

=3D =3D =3D
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AWUS01 KWNH 270032
FFGMPD
NMZ000-AZZ000-270630-

Mesoscale Precipitation Discussion 1143
NWS Weather Prediction Center College Park MD
830 PM EDT Fri Sep 26 2025

Areas affected...Central to Southeast AZ

Concerning...Heavy rainfall...Flash flooding likely

Valid 270030Z - 270630Z

SUMMARY...Clusters of heavy showers and thunderstorms will persist
into the evening hours across central to southeast AZ. Additional
areas of flash flooding will be likely with locally considerable
and life-threatening impacts still possible.

DISCUSSION...The latest GOES-W IR satellite imagery shows clusters
of cold-topped convection continuing to develop and locally
persist across areas of central to southeast AZ. Some of the
strongest convection and heaviest rainfall rates are currently
over portions of Pinal and Gila Counties. This is also where some
of the strongest low-level moisture convergence and pooling of
instability remains in place.

MLCAPE values of 1000 to 1500 J/kg are noted in general across
south-central AZ, and this coupled with larger scale
ascent/forcing associated with the slow approach of an upstream
closed low over eastern CA should continue to favor convection
with high rainfall rates at least for the next few hours.

Gradually there will be an increase in boundary layer CIN as the
evening progresses which will allow for the convective footprint
to begin to wane, but with elevated effective bulk shear of 30 to
40 kts across central to southeast AZ, there may be some
persistence of loosely organized convection through much of the
evening time frame.

Rainfall rates will still be capable of reaching 1 to 2
inches/hour based on the latest cloud top cooling trends over
Pinal and Gila Counties, and the experimental WoFS guidance
supports this for at least a couple more hours.

Some additional spotty totals may reach 2 to 3 inches where any of
the stronger cells continue to backbuild or train over the same
area. This will likely foster some additional areas of flash
flooding for the evening hours. Once again, there will be concerns
for enhanced dry wash/arroyo flash flooding along with potential
for localized burn scar impacts and urban flash flooding where
these heavier rains evolve. Thus, locally considerable and
life-threatening impacts will still be possible for at least a few
more hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4m7wuMKk98wpo0VQFaL3CKxKu7EsAOZQy19fm31h8dXEqp9ERppsD0smd1BP5N1ZoMJx= wIiW4mM7n7aDKTloTVIR0_4$ for graphic product...

ATTN...WFO...EPZ...FGZ...PSR...TWC...

ATTN...RFC...STR...NWC...

LAT...LON 34561110 34441041 33840945 32840904 31770912=20
31230956 31181081 31571162 32221201 32991225=20
33671232 34401195=20

=3D =3D =3D
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AWUS01 KWNH 270556
FFGMPD
VAZ000-NCZ000-WVZ000-271200-

Mesoscale Precipitation Discussion 1144
NWS Weather Prediction Center College Park MD
156 AM EDT Sat Sep 27 2025

Areas affected...much of southern and central VA...portions of
northwestern NC and southeastern WV

Concerning...Heavy rainfall...Flash flooding likely

Valid 270600Z - 271200Z

Summary...Training banded heavy rain with 1-2"/hr rates expected
to result in additional rainfall totals of 3-5" through 8 AM.
Isolated to scattered instances of flash flooding are likely.

Discussion...Disorganized showers and thunderstorms across
southern portions of the Mid-Atlantic have consolidated into a
defined band of heavy rainfall over the past couple of hours. This
band extends a couple hundred miles across southern VA into
northwestern NC, paralleling a surface/low-level frontal boundary
and associated moisture gradient (PWs ranging from 1.5-2.0" across
the gradient, nearing the climatological max moving average at
GSO/RNK). MUCAPE of 500-1000 J/kg is sufficient to sustain deep
convection, and strong upper-level dynamics (right-entrance region
of a jet streak with DPVA via shortwave trough/PV anomaly
upstream) along with modest easterly low-level moisture transport
could allow for localized training of 1-2"/hr rainfall rates.

While hi-res models overall have poorly handled the convective
organization since 00z, the latest HREF suite still indicates
relatively high odds (20-40%) for localized 3" exceedance through
12z (per 40-km neighborhood exceedance probabilities). Given that
banded heavy rainfall has already reached a level of organization
beyond model depictions, these probabilities could be underdone.
Expect that training of banded heavy rainfall lead to additional
rainfall totals of 3-5" with corresponding 3-6 hour Flash Flood
Guidance (FFGs) generally ranging from 1.5-3.0" (with portions of
northwestern NC having already received localized totals of 2-3"
from prior rainfall over the past 3-6 hours). Isolated to
scattered instances of flash flooding are likely.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-NEApKCJ4uPZO6DNJvFdxLGh9mWJaAOPtC9jNS0cpZKIgR3AfLtk4rCXduNNT3xAGa0P= jlzh2eNDBfDORe_QvkbnLnY$ for graphic product...

ATTN...WFO...AKQ...GSP...LWX...RAH...RNK...

ATTN...RFC...ALR...RHA...TIR...NWC...

LAT...LON 38038048 37947951 37637883 37567808 37377714=20
37147680 36607710 36637809 36697890 36297952=20
35957992 35768021 35708054 35798087 35998103=20
36448113 36898090 37378079=20

=3D =3D =3D
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AWUS01 KWNH 271529
FFGMPD
VAZ000-NCZ000-272127-

Mesoscale Precipitation Discussion 1145
NWS Weather Prediction Center College Park MD
1128 AM EDT Sat Sep 27 2025

Areas affected...southeastern Virginia, far northern North
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 271527Z - 272127Z

Summary...Mesoscale evolution of convective cells with
supercellular characteristics should continue to prompt areas of
2-3 inch/hr rain rates. Any localized backbuilding or training
could promote locally significant flash flooding - especially in
urbanized and sensitive locales.

Discussion...A couple of supercellular structures were noted near
Emporia, VA and Roanoke Rapids, NC over the past hour. Because of
the rotational and supercellular character of these cells, slower
and rightward-moving storm motions have enabled spots of 2-3.5
inch/hr rain rates to develop. These cells were migrating
northeastward parallel to a subtle confluence/baroclinic zone
extending from Emporia to KW75/Saluda, VA. Localized vorticity
ingest processes were likely promoting the supercellular
development and maximizing rain rates locally.

Southwesterly steering flow aloft should allow for convection to
continue drifting northeastward and interacting favorably with the aforementioned confluence zone. This, along with 2 inch PW and
1000-1500 J/kg SBCAPE on the warm side of the confluence should
continue to support local 2-3.5 inch/hr rain rates through the
Wakefield and Williamsburg areas. Furthermore, any backbuilding
along the confluence axis could prolong rain rates and lead to a
locally significant flash flood threat - especially in any urban
or flash flood-prone areas. The mesoscale details supporting this
risk should persist for at least a few hours, and perhaps through
21Z/5p EDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9XffrvnDjU2arCQ_v_74REcog2S76BiHViToFBlEApskYCUn4wypKkrBUgoFVDsbFqct= 8oZCu02aOdVxzTPoYV3TEDM$ for graphic product...

ATTN...WFO...AKQ...RAH...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 37857609 37137581 36367669 36007826 36647829=20
37227789 37807691=20

=3D =3D =3D
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AWUS01 KWNH 271531
FFGMPD
VAZ000-NCZ000-272127-

Mesoscale Precipitation Discussion 1145
NWS Weather Prediction Center College Park MD
1130 AM EDT Sat Sep 27 2025

Areas affected...southeastern Virginia, far northern North
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 271527Z - 272127Z

Summary...Mesoscale evolution of convective cells with
supercellular characteristics should continue to prompt areas of
2-3 inch/hr rain rates. Any localized backbuilding or training
could promote locally significant flash flooding - especially in
urbanized and sensitive locales.

Discussion...A couple of supercellular structures were noted near
Emporia, VA and Roanoke Rapids, NC over the past hour. Because of
the rotational and supercellular character of these cells, slower
and rightward-moving storm motions have enabled spots of 2-3.5
inch/hr rain rates to develop. These cells were migrating
northeastward parallel to a subtle confluence/baroclinic zone
extending from Emporia to KW75/Saluda, VA. Localized vorticity
ingest processes were likely promoting the supercellular
development and maximizing rain rates locally.

Southwesterly steering flow aloft should allow for convection to
continue drifting northeastward and interacting favorably with the aforementioned confluence zone. This, along with 2 inch PW and
1000-1500 J/kg SBCAPE on the warm side of the confluence should
continue to support local 2-3.5 inch/hr rain rates through the
Wakefield and Williamsburg areas. Furthermore, any backbuilding
along the confluence axis could prolong rain rates and lead to a
locally significant flash flood threat - especially in any urban
or flash flood-prone areas. The mesoscale details supporting this
risk should persist for at least a few hours, and perhaps through
21Z/5p EDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!521WCHswjMDHevOyXf0WKx2TisetPY-_KeehgTDAFe38B0R7LwXHzUy9sWwCHgKE-eSb= pfVMH82ycMoD74ObCFk0yJY$ for graphic product...

ATTN...WFO...AKQ...RAH...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 37857609 37137581 36367669 36007826 36647829=20
37227789 37807691=20

=3D =3D =3D
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AWUS01 KWNH 271630
FFGMPD
VAZ000-NCZ000-SCZ000-GAZ000-TNZ000-KYZ000-272228-

Mesoscale Precipitation Discussion 1146
NWS Weather Prediction Center College Park MD
1229 PM EDT Sat Sep 27 2025

Areas affected...eastern Tennessee, far southwestern Virginia, far
western North Carolina, far northern Georgia, far northwestern
South Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 271628Z - 272228Z

Summary...Slow-moving thunderstorms should continue to develop
through the afternoon hours. Flash flooding is possible on an
isolated basis.

Discussion...Scattered, slow-moving convection has been persistent
this morning beneath a cold mid/upper low centered over far
northern Georgia this morning. Over the past hour or so,
satellite imagery suggests an imminent uptick in convective
coverage due to insolation, surface-based destabilization, and
deepening cumulus in the region. The storms are forming directly
beneath the mid/upper low, where weak steering flow has led to
slow and erratic storm motions. Meanwhile, 1.4 inch PW values and
1000 J/kg MLCAPE was supporting localized areas of 1-1.5 inch/hr
rain rates that were exceeding local FFG thresholds at times.

Ongoing trends should continue until widespread convective
overturning takes hold and leads to stabilization and decreasing
convective coverage. This process should take a few hours to play
out, though. Areas of isolated flash flooding are expected at
times through the afternoon.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!76sqHZHDAADayExOj2dt3jZ5baS5jSAOGBG1OWsPLsnaWHL9l4K0enYnVYQWnByfzyWR= iX__diZ3IL5UnBXiBhHAECY$ for graphic product...

ATTN...WFO...FFC...GSP...JKL...MRX...OHX...RLX...RNK...

ATTN...RFC...ALR...ORN...TIR...NWC...

LAT...LON 37068288 36738076 34728190 33858421 35118542=20
36298470=20

=3D =3D =3D
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AWUS01 KWNH 271821
FFGMPD
AZZ000-NVZ000-CAZ000-280019-

Mesoscale Precipitation Discussion 1147
NWS Weather Prediction Center College Park MD
220 PM EDT Sat Sep 27 2025

Areas affected...southeastern California, much of Arizona, far
southern Nevada

Concerning...Heavy rainfall...Flash flooding possible

Valid 271819Z - 280019Z

Summary...An increase in convective coverage is expected through
peak heating hours today. A few instances of flash flooding are
possible.

Discussion...Recent satellite imagery depicts deepening cumulus
across a broad part of Arizona and adjacent areas of southeastern
California. Satellite/radar also depicts a persistent, yet small
cluster of cells just north of Yuma that were producing spots of
1-2 inch/hr rain rates. The ongoing evolution of convection is
being supported by a distinct mid/upper low centered over far
southeastern California, in addition to surface-based
destabilization due to sunshine and surface warming. PW values
are in the 1-1.5 inch range, and SBCAPE values are around 1000
J/kg - both supporting deep convection with heavy rainfall as
cells mature. Of note is the fact that cells closer to the
mid/upper low have been very slow to move/propagate so far due to
weak steering flow in that area.

Through the afternoon, increases in convective coverage (along
with increasing prevalence of cell mergers) are expected across
the discussion area. A few more areas of 1-1.5 inch/hr rain rates
are expected - especially across southwestern Arizona where the
best forcing, instability, and moisture combo exists. Isolated to
scattered instances of flash flooding are possible. Much of the
threat should be diurnally driven and persist through 00Z/5p
PDT/6p MDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!465LAeGZjIfzKRajtIB4bzB_LVQG6fPe3Wr9SHFrNOxUQnrmkE1LghNiw6JDewBiz0eo= Bzn3zglQknUhXj5Sm59_Hmo$ for graphic product...

ATTN...WFO...FGZ...HNX...LOX...PSR...SGX...TWC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 36631405 36391160 35371041 32620945 31450974=20
30991091 32341461 32411552 32481632 33891689=20
34701793 36171693=20

=3D =3D =3D
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AWUS01 KWNH 272112
FFGMPD
VAZ000-NCZ000-280111-

Mesoscale Precipitation Discussion 1148
NWS Weather Prediction Center College Park MD
512 PM EDT Sat Sep 27 2025

Areas affected...southeastern Virginia, far northeastern North
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 272111Z - 280111Z

Summary...Potentially significant urban flood potential exists
around Norfolk/Virginia Beach through 00Z/8p EDT.

Discussion...Over the past hour or so, progressive convection has
tended to stall and backbuild along an axis extending from near
Norfolk southwestward to near Windsor, NC. The slowed eastward
progression of this linear complex has enabled focused training
and a peak of rain rates into the 1-1.75 inch/hr range. These
rates aren't surprising given the training and pre-convective
airmass characterized by 2.1 inch PW and ~2000 J/kg SBCAPE.

Unfortunately, these rates will spread northeastward into
populated areas of southeastern Virginia (notably Norfolk and
Virginia Beach). A quick 2-4 inches of rainfall could cause
significant issues with urban runoff in this scenario. Low-lying
areas may also experiencing excessive runoff.

The eastward progression of this band will ultimately rely on
local convective influences (i.e., upscale growth, merging cold
pools, and propagation). It should take at least 2-3 hours for
ongoing convection to clear the region. Again, flash flooding
(locally significant) is likely through 8p EDT.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-uGgh1CJzogzlplRWtrAMWyBFh9jreOdQGicBGA8Fd9puaOYT_Zjk1K3kGwZwAetb5Q6= cIDpGsi5FmcZ4egMQjWqyFs$ for graphic product...

ATTN...WFO...AKQ...MHX...

ATTN...RFC...ALR...RHA...NWC...

LAT...LON 37527558 36777576 36397565 35947601 35887700=20
36587680 37147645 37497609=20

=3D =3D =3D
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AWUS01 KWNH 281345
FFGMPD
NMZ000-281700-

Mesoscale Precipitation Discussion 1149
NWS Weather Prediction Center College Park MD
944 AM EDT Sun Sep 28 2025

Areas affected...southern/central New Mexico

Concerning...Heavy rainfall...Flash flooding possible

Valid 281344Z - 281700Z

Summary...Isolated instances of flash flooding are possible this
morning - especially in sensitive areas/downstream of burn scars.

Discussion...Scattered convection has persisted across much of the
discussion area this morning. Recent radar/satellite shows
additional shower/thunderstorm activity developing across southern
New Mexico and drifting northeastward. The storms are in a
favorable pattern for development owing to difluence aloft and an
upper trough upstream over Arizona. Additionally, a pool of
moisture over the area (1+ inch PW) will continue to support
heavier rainfall especially where localized backbuilding can
materialize. Most of the convection this morning has exhibited <1
inch/hr rain rates, though localized backbuilding and prolonging
of heavy rain rates cannot be ruled out in this regime.=20
Furthermore, the onset of insolation/surface warming should
readily increase SBCAPE values beyond 1000 J/kg this morning,
which may result in an uptick in convective coverage through
17Z/11a MDT.

Though ongoing convective activity is relatively isolated, storms
were unfortunately moving toward sensitive ground conditions near
Ruidoso, NM. These trends are expected to continue this morning,
prompting an isolated flash flood risk in the most sensitive
locales. Rain rates may peak at around 1 inch/hr - especially as
convection increases in coverage and local mergers/backbuilding
become more common.

Cook

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-pLeEWgvdRXR3lvxrf_RZ1C0BAwtZAX1gwuGl5Eh7pOXEvaUQdX8J8ZKRrj4DBjNBgeJ= DfvW1H85xU3ooSrFdY9BViA$ for graphic product...

ATTN...WFO...ABQ...EPZ...MAF...

ATTN...RFC...FWR...NWC...

LAT...LON 34440492 33380431 32260459 31850764 32140802=20
33180738 34220632=20

=3D =3D =3D
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AWUS01 KWNH 281706
FFGMPD
NMZ000-AZZ000-UTZ000-NVZ000-CAZ000-282305-

Mesoscale Precipitation Discussion 1150
NWS Weather Prediction Center College Park MD
105 PM EDT Sun Sep 28 2025

Areas affected...Eastern CA...Southern NV...Far Southern
UT...Northern and Western AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 281705Z - 282305Z

SUMMARY...Locally heavy showers and thunderstorms will be
developing and expanding in coverage going through the early to
mid-afternoon hours. High rainfall rates and slow cell-motions may
result in isolated to scattered areas of flash flooding by
mid-afternoon.

DISCUSSION...A mid to upper-level low is gradually beginning to
lift off to the northeast across northwest AZ, and this energy
coupled with daytime heating/increasing instability and
orographics/upslope flow near areas of higher terrain will drive
the development and expansion of locally heavy showers and
thunderstorms going through the mid-afternoon hours.

SBCAPE values are on the order of 1000 to 1500 J/kg southwest of
the Mogollon Rim and to the south of the low center. However,
visible satellite imagery shows strong diurnal heating taking
place across these areas which will support a notable increase in
instability over the next several hours. The strongest forcing
associated with the low center and broader upper trough axis
should be generally across areas of central and northern AZ going
into the afternoon, and this is generally where the heaviest
rainfall threat will tend to be from developing and expanding
areas of convection. Proximity of the Mogollon Rim will further
support a terrain-induced element to the convective threat.

Scattered areas of convection will also be likely to develop up
across far southern UT, southern NV and portions of eastern CA as
differential heating boundaries become established and focus
smaller scale forcing/focus for convective initiation. In fact,
there is evidence of an MCV over southern NV which may foster a
concern for locally more concentrated convection.

PWs are anomalously high across northwest AZ and especially
southern UT, southern NV and eastern CA where the anomalies are
locally 2 to 2.5 standard deviations above normal. This will
support convective cells with greater rainfall efficiency and thus
elevated rainfall rates.

Rainfall rates will should be capable of reaching up to 1.5
inches/hour with the stronger cells. Locally slow cell-motions
with some concerns for terrain-anchored cells will facilitate the
potential for some spotty 2 to 3+ inch rainfall totals. This may
cause isolated to scattered areas of flash flooding which will
include potential impacts to the area burn scar locations, slot
canyons and arroyos.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8ErEAtlv0HYY17FTtPmEISsl5Jo4iq-iw6i8YScdnenXkZpH9JDmY0ji3LsNfBD81MZ-= zRbv5Nyr07voACSXIzaulqM$ for graphic product...

ATTN...WFO...ABQ...FGZ...GJT...PSR...SLC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 37951141 37510970 36810894 35840904 35210969=20
34501040 33041225 33031402 33661475 34261528=20
34761586 35581634 36321635 36691611 37221524=20
37861332=20

=3D =3D =3D
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AWUS01 KWNH 281745
FFGMPD
TXZ000-NMZ000-AZZ000-282345-

Mesoscale Precipitation Discussion 1151
NWS Weather Prediction Center College Park MD
145 PM EDT Sun Sep 28 2025

Areas affected...Central and Southern NM...Southwest TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 281745Z - 282345Z

SUMMARY...Increasing coverage of showers and thunderstorms is
expected going through the afternoon and evening hours. Heavy
rainfall rates are likely to result in scattered areas of flash
flooding which may impact sensitive burn scar and dry wash
locations.

DISCUSSION...Midday GOES-E Visible and Day Cloud Phase RGB
satellite imagery shows an increasingly agitated CU/TCU field over
southern NM and southwest TX as stronger diurnal heating and an
increase in boundary layer instability ensues. MLCAPE values have
risen to 500 to 1000 K/kg across these areas, and additional
destabilization is expected over the next few hours which will
help set the stage for renewed areas of convective initiation.

Already there has been a corridor of showers and thunderstorms
that progressed through areas of southern NM in response to a lead
shortwave impulse which is advancing quickly off to the northeast.
However, in its wake, the flow aloft remains quite diffluent given
the upstream approach of the broader upper trough over the
Southwest U.S. The approach of these height falls along with a
belt of stronger mid-level southwest flow and resulting shear
should favor the development and expansion of relatively organized
convective cells going through the afternoon hours.

Effective bulk shear values are on the order of 30 to 40 kts which
combined with MLCAPE values eventually reaching 1500+ J/kg should
yield scattered multicell convection. The PW anomalies across the
region are somewhat moist with values of 1.5+ standard deviations
above normal. This will tend top support heavier rainfall rates
with these more organized convective cells that could reach 1 to 2
inches/hour.

The more orographically favored higher terrain, including the
Sacramento Mountains in south-central NM and the Davis Mountains
of southwest TX are expected to be the locations that generally
see the heaviest rainfall potential going through this evening.
Some spotty totals across these areas may reach 2 to 4+ inches
which is supported by some of the 12Z hires model guidance.

Adjacent areas farther west across central to southwest NM will
also see at least locally heavy totals from potentially more
discrete pockets of convection away the terrain.

Scattered areas of flash flooding will become likely in time due
to the development and expansion of convection with these higher
rainfall rates. The more sensitive burn scar locations (including
the Blue 2, South Fork, Salt and McBride burn scar complex) and
normally dry washes will be at greatest risk for impacts.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7xelRpfMJtMEPIBSB9JA6mk_6F9bBX5JDjogUrwu3R4eyi1r2sWxZMLiBMZtdlHlkc3a= NgD4vO8qDuLUrsdVn89zbr0$ for graphic product...

ATTN...WFO...ABQ...EPZ...MAF...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON 35450645 35030492 34370407 33340346 31650325=20
30600342 29960395 29980476 31020587 31480683=20
31420774 31250838 31370885 32320907 34370859=20
35260777=20

=3D =3D =3D
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AWUS01 KWNH 282256
FFGMPD
TXZ000-NMZ000-290455-

Mesoscale Precipitation Discussion 1152
NWS Weather Prediction Center College Park MD
655 PM EDT Sun Sep 28 2025

Areas affected...Central and Southern NM...Southwest TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 282255Z - 290455Z

SUMMARY...Clusters of heavy showers and thunderstorms will persist
through the evening, bringing a likelihood of additional scattered
flash flooding, particularly impacting burn scar areas and arroyos.

DISCUSSION...Late-afternoon GOES-E IR satellite imagery shows
cold-topped convective clusters affecting many areas of central
and southern New Mexico, with the most concentrated and coldest
cloud top temperatures focused over southwest Texas in the last
couple of hours.

Strong upper-level divergence continues over the region as an
upstream upper-level trough approaches from the west. This deeper
layer forcing and ascent continue to interact favorably with a
moderately unstable airmass, sustaining the convection. In fact,
the latest RAP analysis indicates MLCAPE values of 1000 to 1500+
J/kg extending from southwest Texas northward across central New
Mexico. Concurrently, effective bulk shear values reaching 30 to
40 knots are contributing to locally well-organized convective
cells with strong updrafts and heavy rainfall rates.

Sufficient dynamical forcing and diurnally enhanced instability
will continue into the evening, maintaining convective clusters
across the region with localized heavy rainfall. Supporting this
will also be corridors of stronger low-level moisture convergence
which over the last couple of hours have been rather notable
across southwest Texas and into far southern New Mexico.

PW values remain generally 1.5+ standard deviations above normal.
Given these environmental conditions, rainfall rates with stronger
convective cells are likely to continue reaching 1 to 2
inches/hour. The latest high-resolution CAMs suggest additional
localized rainfall totals of 2 to 4+ inches through late this
evening where some cell-merger and terrain-anchored convection
materializes.

These additional rains are expected to cause further scattered
flash flooding throughout the evening. Normally dry washes and
arroyos, as well as burn scar locations, will remain particularly
vulnerable to flash flooding impacts over the next several hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!80FISsy1HC6iJi4VgvFYaDVf84S-OPSaSiuL7dSbLws1D55ZljEYSRH6-dGYuZ7TsEEE= yJZ8FivTYyinzpi6-yYwDQg$ for graphic product...

ATTN...WFO...ABQ...EPZ...MAF...

ATTN...RFC...FWR...STR...TUA...NWC...

LAT...LON 36170513 35400449 33510435 32150431 31230400=20
30360370 29960395 29900470 30540549 30820584=20
31440642 32380699 33130776 34010801 35210770=20
36050661=20

=3D =3D =3D
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AWUS01 KWNH 290412
FFGMPD
NMZ000-290800-

Mesoscale Precipitation Discussion 1153
NWS Weather Prediction Center College Park MD
1211 AM EDT Mon Sep 29 2025

Areas affected...west-central NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 290400Z - 290800Z

Summary...Localized heavy rainfall (1"+/hr rates with as much as
1" in 15-min) will support an isolated flash flood risk through
the early overnight.

Discussion...Convection is persisting into the late evening across
portions of west-central NM, just downstream of a strong PV
(potential vorticity) maxima (400-250 mb). As the low-level jet
strengthens modestly over the next several hours with the diurnal
cycle, updrafts may persist as precipitable water values remain
elevated (~1.0", near climatological max levels per ABQ sounding
climatology) supporting localized rainfall rates of 1"+ (with as
much as 1" in 15-min, per MRMS estimates).

New hi-res guidance (00z HREF) supports continued localized heavy
rainfall (1"+/hr) for at least a couple more hours, though latest
observational trends may support at least isolated convection
continuing through about 09z (with a pool of MLCAPE of 250-750
J/kg over the MPD area likely taking some time still to diminish).
40-km HREF 2" exceedance probabilities are as high as 20% through
09z, suggesting localized/isolated instances of flash flooding
will remain possible.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6Dz7dDKykBox-GVCYrMX2qoIu1TENmbUsOy_f7qnVZATA3lJwPEAFhbjzt5vUycP-3ZA= -hCxAKGB9sZlzJyPDKCfzTc$ for graphic product...

ATTN...WFO...ABQ...EPZ...

ATTN...RFC...FWR...NWC...

LAT...LON 35910610 35320570 34630610 33980616 33440662=20
33500746 34440754 34960773 35490777 35760752=20
35900678=20

=3D =3D =3D
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AWUS01 KWNH 301641
FFGMPD
UTZ000-NVZ000-302200-

Mesoscale Precipitation Discussion 1154
NWS Weather Prediction Center College Park MD
1239 PM EDT Tue Sep 30 2025

Areas affected...East-central Nevada...West-central Utah...

Concerning...Heavy rainfall...Flash flooding possible

Valid 301640Z - 302200Z

SUMMARY...Scattered to numerous small-cored convection within a
favorable repeating flow regime and possible back-building may
result in a few streets of .75-1.25" in 1-3 hours resulting in an
isolated incident or two of localized flash flooding is possible.

DISCUSSION...GOES 7.3um WV suite depicts a subtle shortwave at the
right entrance to a 50kt S-N jet along the northern NV/UT border
lifting northeast with typical back-arched upper-level cirrus
indicative of the very favorable divergent flow aloft. Upstream
the well defined drying also denotes the elongated main trough
axis extending from SE OR through central NV; with the core of the
west to east jet starting to nose southward delineating the mean
trough axis.=20

Low level response has been for enhanced return flow out of the
Lower Colorado River bending eastward along a surface to boundary
layer trough between the Salt Lake surface low and the southern NV
low. Pooled moisture mainly below 700mb has supported total Pwats
to 1" across the Salt Flats into SLC vicinity just along/ahead of
the leading shortwave; though enhanced values up to .8-.9" still
remain along the upwind edge. Some mid-level drying and clearing
over east-central NV has provided some insolation/heating to
support SBCAPEs nearing 1000 J/kg. In response to the DPVA, and
low level convergence at the nose of the low level moisture flux
feed; numerous small cored convective cells have begun to cluster
across S White Pine county, NV with hints of further Cu field
development across NE Lincoln county, NV into Millard county, UT.=20
While the cores are shallow (-45 to -50C tops) and narrow, there
is increasing coverage to support better moisture flux convergence
for enhancing rates to near .75"/hr over the next few hours.=20=20=20

Deep layer flow is broadly southwest to southeast parallel to the
surface trough and considering the overall longer wave trof is
filling at the base and shifting northeast, the deeper layer flow
should remain similar to allow for repeating environment. This
concurrent for upstream instability pool and low level moisture flux/convergence to support some back-building potential... all of
which will slowly shift eastward. Given all this, a few repeat
streets may allow for localized .75-1.25" totals in 1-3 hours.=20
Naturally low FFG values are about .75-1"/hr and 1-1.5"/3hrs
suggesting an isolated incident or two of localized flash flooding
may be possible through the afternoon/early evening while
instability pool remains viable.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8bR5yKjzVKRs6jBuMiXqmLNMmDXlRQeTqjnooRlFBRj2gxTI8Rwgd4km1QXzyJHJAWLs= H6Ty6cXJZFvKBuGeCP0eO2E$ for graphic product...

ATTN...WFO...LKN...SLC...VEF...

ATTN...RFC...RSA...STR...NWC...

LAT...LON 40831256 40821165 40001141 39451159 38801201=20
38191282 37701405 37931487 38881502 39621464=20
40311387 40591326=20

=3D =3D =3D
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AWUS01 KWNH 022228
FFGMPD
FLZ000-030310-

Mesoscale Precipitation Discussion 1155
NWS Weather Prediction Center College Park MD
627 PM EDT Thu Oct 02 2025

Areas affected...eastern FL

Concerning...Heavy rainfall...Flash flooding possible

Valid 022222Z - 030310Z

SUMMARY...Localized but high rainfall rates are expected across
coastal sections of eastern/southeastern FL over the next 3-5
hours. Hourly rainfall of 2 to 3 inches is expected, but locally
higher values cannot be ruled out which may lead to localized
flash flooding.

DISCUSSION...22Z visible satellite and area radar imagery
indicated a narrow axis of showers/thunderstorms over Martin and
northern Palm Beach counties, extending offshore and oriented quasi-perpendicular to the coast. MRMS showed hourly rainfall
peaking in the 1-2 inch range. This axis and additional storms
were located just south of a low level gradient in moisture,
aligned from east to west as seen in the surface to 700 mb layer
on LPW imagery from OSPO. Higher values of low level moisture
extended southward from roughly Melbourne, while drier and more
stable air existed to the north. Total PW values were estimated to
be near 2 inches along the Treasure Coast where low level moisture
flux was maximized and MLCAPE ranged from 1000-1500 J/kg via the
22Z SPC mesoanalysis across southeastern FL.

Some subtle low level cyclonic rotation appeared in visible
imagery and 7.3 micron water vapor imagery which may be enhancing
lift across the eastern/southeastern Peninsula Relatively strong
low level easterly flow of 20-25 kt was in place and is expected
to maintain over the next few hours, oriented largely
perpendicular to central to south-central portions of the FL
coast, maximizing convergence. Transient axes of low level
convergence within the anomalous low level moisture plume are
expected to support the possibility of additional narrow bands of showers/thunderstorms which may be slow moving due in part to
opposing low level and upper level winds and mean steering flow
matching the orientation of convergence axes. Hourly rainfall of
2-3 inches should be easily attainable within any slow moving
heavy rain axes but the environment will have the potential to
support 3+ inches of rain in an hour as well. These high rainfall
intensities would support an isolated flash flood threat should
they overlap with the urbanized I-95 corridor, where runoff would
be more likely despite the otherwise high flash flood guidance
values across the region. However, the potential for these very
high rain rates should remain quite localized from northern
Miami-Dade to Indian River counties through 03Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!__p112XPLqRR13rzSuD82BUNXbfgZHunFD9agprIMC6A_1z7u5mnb8TZSBBGnQG_7D8C= DqKHwqNbfJy_qIx3HCFQ4VE$ for graphic product...

ATTN...WFO...MFL...MLB...

ATTN...RFC...ALR...NWC...

LAT...LON 27778055 27718017 27498006 26957984 26317981=20
25588006 25648054 26138057 26568054 26998074=20
27378075=20

=3D =3D =3D
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AWUS01 KWNH 022258
FFGMPD
NVZ000-CAZ000-030400-

Mesoscale Precipitation Discussion 1156
NWS Weather Prediction Center College Park MD
658 PM EDT Thu Oct 02 2025

Areas affected...San Joaquin Valley into central Sierra Nevada

Concerning...Heavy rainfall...Flash flooding possible

Valid 022257Z - 030400Z

SUMMARY...Training and repeating of showers and thunderstorms may
result in localized flash flooding from the northern San Joaquin
Valley into the central Sierra Nevada later this evening. Hourly
rainfall of 0.5 to 1.0+ inches is expected which could result in a
rapid 1-2 inches through 04Z.

DISCUSSION...GOES West visible and local radar imagery over
central CA was fairly quiet as of 2230Z in terms of
showers/thunderstorms but that may change over the next 3-6 hours.
A few cells appeared to be developing near the I-5 corridor across
the northern San Joaquin Valley as seen on KHNX radar and
additional development appears likely. MLCAPE was rather weak at
500 J/kg or less via 22Z SPC mesoanalysis data but PW values were
high at 1.0 to 1.4 inches. These values would equate to a
standardized PW anomaly of +3 to +4 for early October.

This region of CA was positioned ahead of the base of an
approaching mid to upper-level trough located just off of the
northern CA coast with strengthening right-exit region divergence
of a 90-100 kt jet just east of the trough base. While surface
heating through solar insolation has maximized, some additional
advection of low-level moisture may locally boost instability
values slightly higher over the next few hours. Showers and
possibly a thunderstorm aligning within the unidirectional SSW
flow along with upslope low level flow into the Sierra Nevada may
act to boost rain rates with potential for 0.5 to 1.0 inches in an
hour. While the threat for flash flooding appears to be highly
localized, these higher rainfall intensities falling on sensitive
burn scars or urban areas would be at most risk for localized
flash flooding through 04Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4z5_pliYw5pYczaQJ8yWjKZdFcMmbpTjjftCcR_BX1T9hKCiEQ7glaarEk3k-77ghhr-= u5UTiOkB6XuuJuhzqGtywBM$ for graphic product...

ATTN...WFO...HNX...MTR...REV...STO...

ATTN...RFC...RSA...NWC...

LAT...LON 39172033 39162009 38901971 38531945 37891909=20
37041902 36321932 36022001 36402078 37172113=20
37972082 38592068 39052052=20

=3D =3D =3D
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AWUS01 KWNH 030342
FFGMPD
FLZ000-030900-

Mesoscale Precipitation Discussion 1157
NWS Weather Prediction Center College Park MD
1141 PM EDT Thu Oct 02 2025

Areas affected...Southeast FL

Concerning...Heavy rainfall...Flash flooding possible

Valid 030341Z - 030900Z

SUMMARY...Locally concentrated areas of very heavy showers and
thunderstorms across southeast FL will continue in the near-term.
Concerns for urban flash flooding will exist near and south of the
Miami metropolitan area.

DISCUSSION...GOES-E Proxy Visible satellite imagery along with
radar data shows some concentrated areas of very heavy showers and thunderstorms continuing to impact portions of southeast FL. Much
of the activity is currently situated near and south of Miami with
some relatively organized banding of convection that is
well-aligned with the very moist/unstable low-level easterly flow
impacting the FL Peninsula.

Satellite and surface data also show signs of a weak low-level
vort center near Biscayne Bay which is helping to concentrate an
axis of strong moisture convergence into the coastal areas in
between Miami and Homestead. MLCAPE values of near 1000 J/kg are
in place, with PWs of 1.8 to 2.0 inches.

Some cell-training concerns will exist over the next few hours
with the convective activity impacting southeast FL, and
especially with a persistently convergent low-level Atlantic fetch
into the region. Rainfall rates have already been reaching as high
2 to 3 inches/hour, and with any persistence of these stronger
convective cores, there may be some rainfall totals that locally
approach or exceed 5 inches. This is supported by some of the 00Z
HREF guidance.

Expect there to be at least some concerns for urban flash flooding
with these heavier rainfall rates and storm totals set up over the
next few hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!98UZoF4G0XdnPVYl7qoTSxbX3It1YKYOKQF0Sq7PDroixNuu6-KMzdtq7meHc1Y5QShB= t2qwfcqXCksXXWswGOrhleU$ for graphic product...

ATTN...WFO...KEY...MFL...

ATTN...RFC...ALR...NWC...

LAT...LON 26168015 26028007 25758007 25328022 25278039=20
25478053 25968043 26158027=20

=3D =3D =3D
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