Storm Prediction Center Mesoscale Discussion 1374

   Mesoscale Discussion 1374
   NWS Storm Prediction Center Norman OK
   0302 AM CDT Mon Jun 29 2026

   Areas affected...much of central South Dakota

   Concerning...Severe Thunderstorm Watch 412...

   Valid 290802Z - 291000Z

   The severe weather threat for Severe Thunderstorm Watch 412
   continues.

   SUMMARY...Storms over south-central South Dakota are expected to
   become an intense complex over the next couple hours, producing
   winds of 75-90 mph and large hail across central parts of the state.

   DISCUSSION...Earlier supercells have merged near the cold front and
   surface low over southwest SD, with recent radar trends indicating
   the early stages of upscale growth into a compact but significantly
   severe MCS. Aside from the supercell over Bennett County SD, radar
   also shows a warm advection wing developing east/northeast of it,
   with additional development south of this cell along the cold front.
   This evolution is taking place near a substantial 850 mb theta-e
   gradient, with MUCAPE up to 4000 J/kg along and south of the surge.

   Given recent trends, strong instability and steep lapse rates aloft,
   and a favorable low-level jet, confidence is increasing that this
   complex will strengthen, and possible accelerate northeastward
   through the morning hours. Additional watches may be required
   downstream into more of northern/northeast SD and southeast ND as
   the scenario evolves.

   ..Jewell.. 06/29/2026

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

   ATTN...WFO...FSD...ABR...LBF...UNR...

   LAT...LON   42900231 43320213 43610187 44000134 44560086 45220005
               45179925 44989881 44579880 43819925 43180022 42920144
               42760224 42900231 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...75-90 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN