Storm Prediction Center Mesoscale Discussion 2017

   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 www.spc.noaa.gov 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