Storm Prediction Center Mesoscale Discussion 2032

   Mesoscale Discussion 2032
   NWS Storm Prediction Center Norman OK
   0854 PM CDT Tue Aug 18 2026

   Areas affected...Parts of western/southwest SD

   Concerning...Severe potential...Watch unlikely 

   Valid 190154Z - 190330Z

   Probability of Watch Issuance...20 percent

   SUMMARY...An isolated severe hail/wind threat may continue this
   evening. Watch issuance is unlikely.

   DISCUSSION...A cell which formed earlier over the Black Hills in
   western SD has recently intensified into a supercell while
   approaching Rapid City. The 00Z UNR sounding showed relatively
   modest instability (MUCAPE less than 1000 J/kg) and mid-level lapse
   rates, but strong deep-layer shear around 50 kt. This ongoing
   supercell should continue to pose a threat for severe hail in the
   short term per recent MRMS MESH estimates. But, it remains unclear
   whether it will be able to persist downstream of the higher terrain
   of the Black Hills given increasing MLCIN with nocturnal cooling
   occurring across southwest SD. Some short term guidance suggests a
   small cluster may evolve over the next couple of hours, with some
   increase in severe/damaging outflow winds possible if this occurs.
   Regardless, the presence of weak instability and overall isolated
   nature of the severe threat suggest that watch issuance is unlikely.

   ..Gleason.. 08/19/2026

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

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

   LAT...LON   44100353 44470321 44110146 43350148 43080203 43180275
               43810362 44100353 

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