Storm Prediction Center Mesoscale Discussion 1661

   Mesoscale Discussion 1661
   NWS Storm Prediction Center Norman OK
   0330 PM CDT Sun Jul 19 2026

   Areas affected...portions of the Black Hills into south-central
   South Dakota and northern Nebraska

   Concerning...Severe potential...Watch unlikely 

   Valid 192030Z - 192230Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Some potential for damaging/severe wind gusts may
   accompany developing, high-based convection through this evening.

   DISCUSSION...Latest visible satellite imagery depicts a field of
   towering cumulus with recent lightning activity across portions of
   southwestern South Dakota. Modifying the nearby 18z UNR observed
   sounding for nearby observations depicts a deep, well-mixed boundary
   layer with steep low-level lapse rates, 500 to 750 J/kg MLCAPE, and
   LCLs around 3 km AGL. This thermodynamic environment will support
   high-based convection, with some potential for isolated
   damaging/severe wind gusts likely to evolve through the
   afternoon/evening given surface dewpoint depressions of 40-50 F.

   Latest high-res guidance suggests that some clustering of convection
   along developing cold pools may occur over the next several hours;
   however, uncertainty remains regarding the longevity of this
   convection. With this activity occurring along the southern
   periphery of stronger mid-to-upper level flow, effective shear is
   limited to around 20-25 kts per latest mesoanalysis. This lends some
   credence to a more limited severe risk compared to areas farther
   north. Thus, watch issuance appears unlikely at this time but could
   be considered should a longer duration risk for damaging/severe wind
   gusts evolve through this afternoon and evening.

   ..Chalmers/Thompson.. 07/19/2026

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

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

   LAT...LON   44230018 44089971 43789949 43479954 42930000 42500075
               42180211 42120294 42120338 42340366 42760371 43340341
               43860270 44210192 44310147 44340124 44230018 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH