Storm Prediction Center Mesoscale Discussion 2330

   Mesoscale Discussion 2330
   NWS Storm Prediction Center Norman OK
   0240 PM CDT Mon Sep 28 2026

   Areas affected...western South Dakota vicinity

   Concerning...Severe potential...Watch unlikely 

   Valid 281940Z - 282145Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Isolated strong to severe thunderstorms may produce
   sporadic hail through evening. Severe potential is expected to
   remain limited, and a watch is not anticipated.

   DISCUSSION...Thunderstorms are developing near the Black Hills
   across northeast WY this afternoon. This activity is developing near
   the surface low and attendant cold front within an area that has
   seen less cloudiness/stronger heating. An area of cumulus
   development is noted in visible satellite imagery where clearing has
   been more prevalent across northwest SD into southwest ND.
   Additional thunderstorm development is expected within this area
   over the next few hours.

   Latest mesoanalysis shows MLCAPE around 1000-1500 J/kg and 7-7.5
   C/km midlevel lapse rates across the region, which aligns well with
   18z RAOBS from UNR and BIS. Effective shear magnitudes around 30 kt
   and elongated hodographs above 2 km in combination with this
   thermodynamic environment suggests that a few organized updrafts
   could support marginally severe hail. With time, and northeast
   extent, convection may become more elevated given greater low-level
   inhibition where cloudiness has persisted, and as the cold front
   begins to surge east/southeast during the evening.

   ..Leitman/Gleason.. 09/28/2026

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

   ATTN...WFO...ABR...BIS...UNR...BYZ...

   LAT...LON   43940426 44030437 44440477 44580487 45020470 45900400
               46360322 46590226 46580178 46450131 46210092 45720060
               44920073 44340101 43950156 43630251 43550340 43940426 

   MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN