Storm Prediction Center Mesoscale Discussion 961

   Mesoscale Discussion 0961
   NWS Storm Prediction Center Norman OK
   0453 PM CDT Tue Jun 02 2026

   Areas affected...Northeast Wyoming into western South Dakota

   Concerning...Severe Thunderstorm Watch 269...

   Valid 022153Z - 030000Z

   The severe weather threat for Severe Thunderstorm Watch 269
   continues.

   SUMMARY...The threat for severe thunderstorms will likely increase
   over the next 2-3 hours across far northeast Wyoming and into
   western South Dakota.

   DISCUSSION...Latest GOES imagery shows several new attempts at
   convective initiation along a weak surface confluence zone draped
   across eastern WY into far southeast MT. At least one of these early
   attempts is exhibiting steady growth with increasing lightning
   counts, suggesting that sustained deep convection is likely in the
   next hour or so across northeast WY. Further south, a few cells
   within a broader convective cluster are also showing signs of
   intensification based on MRMS VIL trends. 

   This activity will gradually spread northeast over the next few
   hours where MLCAPE was recently sampled just over 1500 J/kg with
   weak inhibition by a special sounding near Newell, SD (north of the
   Rapid City area). This sounding also depicted an elongated hodograph
   featuring around 45 knots of effective bulk shear, which will
   support organized storms, including the potential for splitting
   supercells. Latest CAM guidance appears to be capturing this
   environment well and shows an increase in storm coverage and
   intensity across western WY over the next 2-3 hours. Based on
   current satellite/radar trends, discrete supercells with an
   attendant large/very large hail, and perhaps tornado threat, appear
   most likely across northwest SD. Further south, upscale growth of
   convection in east-central WY will likely support an increasing wind
   threat across southwest SD.

   ..Moore.. 06/02/2026

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

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

   LAT...LON   44560471 45890343 46160258 46130202 45970164 45640139
               45310147 44940177 43320289 43100319 43010371 43000424
               43010454 43160479 43560498 44240487 44560471 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN