Storm Prediction Center Mesoscale Discussion 1959

   Mesoscale Discussion 1959
   NWS Storm Prediction Center Norman OK
   0534 PM CDT Wed Aug 12 2026

   Areas affected...southwestern South Dakota into northern Nebraska

   Concerning...Severe Thunderstorm Watch 576...578...

   Valid 122234Z - 130030Z

   The severe weather threat for Severe Thunderstorm Watch 576, 578
   continues.

   SUMMARY...Damaging wind and large hail threat continues within WW576
   and WW578.

   DISCUSSION...A cluster of supercells continue southeastward across
   southwestern South Dakota. These have produced hail up to 1.75
   inches in diameter and damaging wind up to 87 mph. These will likely
   continue to pose a risk for large hail and damaging wind downstream
   over the next few hours, given the very favorably unstable and
   deeply sheared environment across western Nebraska, where MLCAPE
   around 1000-2400 J/kg and deep layer shear around 45-50 kts is
   depicted by SPC Mesoanalyis. Trends in hi-res guidance suggest that
   this cluster may eventually interact with convection coming out of
   Colorado later this evening, with a continued damaging wind risk
   through the evening.

   ..Thornton.. 08/12/2026

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

   ATTN...WFO...LBF...UNR...CYS...

   LAT...LON   42880340 43090396 43350404 43540393 43640366 43700343
               43750298 43760295 43640232 43310183 43050191 42910202
               42860217 42810234 42880340 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN