ACUS11 KWNS 212134
SWOMCD
SPC MCD 212133=20
MNZ000-IAZ000-SDZ000-212300-

Mesoscale Discussion 2111
NWS Storm Prediction Center Norman OK
0433 PM CDT Sun Sep 21 2025

Areas affected...portions of southeastern South Dakota into far
southwestern Minnesota and extreme northwestern Iowa

Concerning...Severe potential...Watch unlikely=20

Valid 212133Z - 212300Z

Probability of Watch Issuance...20 percent

SUMMARY...Scattered thunderstorms may continue to increase in
coverage and intensity through the remainder of the afternoon. The
strongest storms may produce an instance of marginally severe
wind/hail or a brief tornado.

DISCUSSION...Scattered multicellular storms have developed amid peak
heating and are gradually increasing in coverage with the passage of
a pronounced 500 mb shortwave trough/vorticity maximum to the north.
These storms are developing atop a mixed boundary layer, but with
relatively mediocre mid-level lapse rates (e.g. around 6 C/km). As
such, buoyancy is weak, with about 500-1000 J/kg MLCAPE constrained
to tall, thin profiles per RAP forecast soundings. Deep-layer shear
is not strong, with 20-30 kts of effective bulk shear noted per 21Z mesoanalysis. Nonetheless, appreciable turning of the winds with
height, along with some strengthening, is supporting low-level
hodographs with some curvature. Multicells will therefore remain the
primary mode of convection of the more mature storms that become
sustained, though a transient supercell or two is possible. A couple
instances of marginally severe hail, wind, or a brief tornado cannot
be ruled out.

..Squitieri/Kerr.. 09/21/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8xTj2TVAXSB_SCi4V8cN9Xaz5uwuCpfIZtbK7eK6DdgmRCA-TSFLCuqkpg7ST8FYxzab1CnI3= cFFstEepgmJtdhVJws$ for graphic product...

ATTN...WFO...ARX...MPX...DMX...FSD...

LAT...LON 44079730 44979470 45039377 44779305 44339277 43889280
43499314 43149395 43049506 43129603 43299670 43529699
44079730=20

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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