ACUS11 KWNS 172254
SWOMCD
SPC MCD 172254
SDZ000-180000-

Mesoscale Discussion 2017
NWS Storm Prediction Center Norman OK
0554 PM CDT Mon Aug 17 2026

Areas affected...portions of western and central South Dakota

Concerning...Severe Thunderstorm Watch 591...

Valid 172254Z - 180000Z

The severe weather threat for Severe Thunderstorm Watch 591
continues.

SUMMARY...The risk for severe wind and hail will continue across
western and central SD over the next several hours. An instance of
2+ inch diameter hail or a 75+ mph gust is possible.

DISCUSSION...Multicells and supercells continue to progress across
western and central SD. Several severe gusts have been reported,
with MRMS MESH data suggesting hail over 1.5 inches diameter has
fallen from some of the stronger storms. A buoyant and sheared
airmass precedes the ongoing storms, with 1500+ J/kg MLCAPE
coinciding with 45-60 kts of effective bulk shear over much of
central SD. The current thinking is that supercell structures will
be maintained for at least a few more hours, accompanied by a severe
wind/hail threat. The best chance for severe, including significant
severe wind/hail, will be with the more sustained, mature supercells
currently over central and northwestern SD.

..Squitieri.. 08/17/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!74oaylKZsb9Exx5ZGAM0ZIQ8Xs5zXVCGEa7zoDrjuNfQi7Wekd0tAqd00tLwBYm-zMfIFqz1WDINSqTuNGdSi_qX_F4$ for graphic product...

ATTN...WFO...FSD...ABR...UNR...

LAT...LON 43730335 45640236 45790185 45820036 45779904 45559851
45079829 44379868 43949904 43549961 43360025 43220108
43210191 43350294 43730335

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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