Storm Prediction Center Mesoscale Discussion 1385

   Mesoscale Discussion 1385
   NWS Storm Prediction Center Norman OK
   0400 PM CDT Mon Jun 29 2026

   Areas affected...Eastern South Dakota...Southwest
   Minnesota...Northeast Nebraska...and far Northwest Iowa

   Concerning...Severe potential...Watch possible 

   Valid 292100Z - 292330Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Surface-based storm initiation will become increasingly
   likely in the 22-00Z time frame. Large to very large hail in excess
   of 2 inches and damaging winds with significant gusts of 75+ mph
   will be the predominant hazards. Observational data are being
   monitored for a possible watch issuance.

   DISCUSSION...The 18Z OAX sounding sampled a pronounced cap at the
   base of an EML, which has inhibited convective development along a
   cold front moving into the area from the west. However, latest CAM
   guidance suggests that isolated thunderstorm development is possible
   by as early as 22Z, but more likely closer to 00Z as continued
   daytime heating and the glancing influence of a short-wave trough to
   the west, locally erode the cap. Latest objective analysis indicates
   the air mass is strongly unstable with MLCAPE as high as 3000-4500+
   J/kg. When coupled with 35-45 kt deep-layer shear, the setup appears
   supportive of supercells as the initial storm mode with the
   potential for large to very large hail. 

   Later this evening into tonight, storms may begin to coalesce on
   growing cold pools, leading to a subsequent increase in damaging
   wind potential with significant gusts of 75+ mph possible. The
   greatest potential for a tornado or two will exist across eastern SD
   into western MN; however, the tendency for the low-level wind field
   to veer ahead of the cold front is expected to limit the overall
   threat.

   ..Mead/Guyer.. 06/29/2026

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

   ATTN...WFO...MPX...FSD...OAX...ABR...

   LAT...LON   42189807 43649782 44639769 45179779 45349675 45269584
               43429592 42509638 41889769 42189807 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN