ACUS11 KWNS 171947
SWOMCD
SPC MCD 171946
IDZ000-172215-

Mesoscale Discussion 2304
NWS Storm Prediction Center Norman OK
0246 PM CDT Thu Sep 17 2026

Areas affected...Parts of southern and central Idaho

Concerning...Severe potential...Watch unlikely

Valid 171946Z - 172215Z

Probability of Watch Issuance...20 percent

SUMMARY...The risk of a few severe storms capable of producing large
hail and severe wind gusts will increase through the remainder of
the afternoon. A watch is not currently expected, though trends are
being monitored.

DISCUSSION...Thunderstorms are gradually increasing in coverage
across parts of southern and central ID. These storms are being
aided by increasing large-scale forcing for ascent preceding a
closed midlevel low over northern CA and localized terrain
circulations. These storms will continue developing and spreading
northward across southern into central ID this afternoon, given deep
southerly steering flow. The 18Z BOI sounding sampled steep
deep-layer lapse rates and an elongating/mostly straight hodograph
(around 30-40 kt of cloud-layer shear per VWP and mesoanalysis
data). Initially, cellular storms will pose a risk of large hail and
locally severe wind gusts. With time, storms may organize into small
clusters and pose an increasing risk of severe wind gusts.

Currently, the risk appears too localized for a watch, though
convective trends are being monitored.

..Weinman/Hart.. 09/17/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!51TO3ftfq9ZGhNBxirjJZeLNRzzhtYjgKk0X43ry81VWp-uAcDnyjQaTkqvoTcqLciZIwDfANaUXCbst4A1raotPvLw$ for graphic product...

ATTN...WFO...PIH...MSO...BOI...

LAT...LON 42241289 42401350 42681421 43511524 43861557 44261571
44561562 44741525 44731470 44431345 44131257 43801213
43221198 42691207 42271250 42241289

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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