Storm Prediction Center Mesoscale Discussion 1937

   Mesoscale Discussion 1937
   NWS Storm Prediction Center Norman OK
   0548 PM CDT Tue Aug 11 2026

   Areas affected...Parts of western SD

   Concerning...Severe Thunderstorm Watch 569...

   Valid 112248Z - 120015Z

   The severe weather threat for Severe Thunderstorm Watch 569
   continues.

   SUMMARY...Intense supercells will remain capable of producing mainly
   large to very large hail (up to 2-3.5 inches and diameter) this
   evening as they track east-southeastward.

   DISCUSSION...A supercell which developed over the Black Hills
   earlier this afternoon strengthened and produced large hail up to
   3.5 inches in diameter in southwest SD. Since then, additional
   supercells have developed over far southeast MT into northwest SD,
   and over the Black Hills. The environment across western SD remains
   quite favorable for the maintenance for intense supercells this
   evening, with strong instability and deep-layer shear both present.
   These supercells are expected to generally track east-southeastward
   while posing a threat for mainly large to very large hail up to
   2.5-3.5 inches in diameter. Some risk for severe/damaging winds will
   also exist with RFD surges with these intense cells.

   ..Gleason.. 08/11/2026

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...UNR...

   LAT...LON   45680402 45870388 45830328 45530270 43640213 43130210
               43070322 43610392 44120403 45680402 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN