Storm Prediction Center Mesoscale Discussion 1493

   Mesoscale Discussion 1493
   NWS Storm Prediction Center Norman OK
   0247 PM CDT Sat Jun 28 2025

   Areas affected...western SD...far northeast WY/southeast MT

   Concerning...Severe potential...Watch possible 

   Valid 281947Z - 282145Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Isolated large hail and localized severe gusts may
   accompany initial storms along the north side of the Black Hills. A
   Severe Thunderstorm Watch issuance is possible.

   DISCUSSION...Initial Cb development is underway near the MT/WY/SD
   border area, within an upslope flow, post-frontal regime along the
   northern portion of the Black Hills. This orographic ascent will be
   necessary to sustain storms amid greater MLCIN farther southeast per
   the 18Z UNR sounding. With moderate mid-level west-southwesterlies
   atop the low-level northerlies, effective bulk shear will be
   sufficient for supercell structures. With a ribbon of low 60s
   surface dew points from far northeast WY across northwest SD,
   moderate MLCAPE of 1500-2000 J/kg should be maintained. Large hail
   should be the main hazard. Overall convective coverage may remain
   isolated and largely tied to the terrain through late afternoon.

   ..Grams/Hart.. 06/28/2025

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

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

   LAT...LON   45890260 45460259 44410278 44030353 44390421 44340520
               44420533 44770534 45170507 45820396 45890260 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN