Storm Prediction Center Mesoscale Discussion 1935

   Mesoscale Discussion 1935
   NWS Storm Prediction Center Norman OK
   0518 PM CDT Tue Aug 11 2026

   Areas affected...Parts of far southeast MT into southern ND and far
   northern SD

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 112218Z - 112345Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Trends are being monitored for watch issuance soon with
   widely spaced supercells that have developed this afternoon. Very
   large hail and severe gusts may occur with this activity.

   DISCUSSION...An intense supercell has developed over far southeast
   MT along/near a front extending eastward from a weak surface low
   near KBIL, with a separate supercell having also recently developed
   over south-central ND near the surface boundary. While surface
   temperatures are not overly warm (generally in the 80s), modifying
   the 18Z observed BIS sounding for current conditions suggests
   minimal MLCIN is present along/south of the boundary in southern ND.
   Enhanced mid-level west-northwesterly flow across the northern
   Plains is supporting 40-50 kt of deep-layer shear, which will
   continue to support supercells in the near term. Mid-level lapse
   rates around 7.6 C/km in the 700-500 mb layer observed on the 18Z
   BIS sounding and seasonably cool temperatures aloft have fostered
   moderate to strong instability across southern ND (MLCAPE around
   2000-3000 J/kg). Very large hail potentially up to 2-3 inches in
   diameter will be possible with any sustained supercell, and storm
   splitting appears probable given the strong westerly deep-layer
   shear present/nearly straight mid-level hodographs observed.
   Occasional severe gusts may also occur as low-level lapse rates
   steepen further. Given ongoing convection, and the potential for
   additional activity to develop/move eastward into southwest ND from
   southeast MT, watch issuance is being considered soon.

   ..Gleason/Mosier.. 08/11/2026

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

   ATTN...WFO...FGF...ABR...BIS...BYZ...

   LAT...LON   46000400 46080427 46400425 46630399 46880397 47130154
               46589801 46029779 45729796 45629853 45630041 45970189
               46000400 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN