Storm Prediction Center Mesoscale Discussion 2267

   Mesoscale Discussion 2267
   NWS Storm Prediction Center Norman OK
   0629 PM CDT Mon Sep 07 2026

   Areas affected...portions of southeastern South Dakota and far
   north-central/northeastern Nebraska

   Concerning...Severe potential...Watch possible 

   Valid 072329Z - 080100Z

   Probability of Watch Issuance...60 percent

   SUMMARY...A threat for primarily large to very large hail and
   perhaps a tornado exists across portions of southeastern South
   Dakota and far north-central/northeastern Nebraska.

   DISCUSSION...Isolated thunderstorm development has been noted near
   the SD/NE border along a weak surface boundary/confluence zone in
   the past 30-60 minutes. While the anticipated northeasterly motion
   of this activity will result in developing storms crossing to the
   cool side of a surface warm front, latest objective analysis and RAP
   forecast soundings suggest that MUCAPE ranges from 2000 to as high
   as 4000 J/kg across this region. Coupled with modestly steep
   mid-level lapse rates around 7 C/km, ESRH of 200-400 m2/s2, and ~40
   kts of effective shear, this environment favorable for primarily
   large to very large hail. Clockwise-curved low-level hodographs may
   also support a risk for a tornado should a supercell become rooted
   in the boundary layer; although, this remains uncertain given the
   presence of poor lapse rates and modest static stability within the
   low-levels (particularly on the cool side of the warm front). Trends
   will continue to be monitored, and a targeted WW may be needed
   should ongoing activity continue to persist/intensify.

   ..Chalmers/Gleason.. 09/07/2026

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

   ATTN...WFO...FSD...OAX...LBF...

   LAT...LON   42729924 42899930 43329920 43989860 44189814 44269768
               44149732 43899696 43549683 43109696 42799763 42729808
               42619886 42729924 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN