Storm Prediction Center Mesoscale Discussion 589

   Mesoscale Discussion 0589
   NWS Storm Prediction Center Norman OK
   0529 PM CDT Mon Apr 28 2025

   Areas affected...Northeast Nebraska...southeast South
   Dakota...northwest Iowa

   Concerning...Severe potential...Watch possible 

   Valid 282229Z - 290000Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Scattered strong/severe thunderstorms are expected this
   evening. Some consideration is being given to a severe thunderstorm
   watch.

   DISCUSSION...Synoptic front is surging southeast across southeast
   South Dakota early this evening. A pre-frontal confluence zone is
   contributing to a corridor of high-based cumulus from central NE
   into extreme northwest IA. Lightning is now being observed with
   frontal convection west-north of ONL, and this activity is expected
   to gradually intensify over the next few hours as it propagates
   downstream along a zone of modest instability. Strong deep-layer
   shear suggests some supercell potential, and hail will likely be the
   primary concern, though steep boundary-layer lapse rates do favor
   gusty winds. If this activity continues to increase in
   coverage/intensity a severe thunderstorm watch may be warranted.

   ..Darrow/Gleason.. 04/28/2025

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

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

   LAT...LON   42919834 43359612 41969584 41709911 42919834 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN