Storm Prediction Center Mesoscale Discussion 501

   Mesoscale Discussion 0501
   NWS Storm Prediction Center Norman OK
   1113 AM CDT Thu Apr 23 2026

   Areas affected...eastern Nebraska...western and central Iowa into
   southern Minnesota

   Concerning...Severe potential...Watch likely 

   Valid 231613Z - 231815Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorm development is likely along the cold front
   from midday into early this afternoon across eastern NE into
   northwest IA. A mix of supercells and line segments could support
   tornadoes, large hail, and damaging gusts. A Weather Watch is
   likely.

   DISCUSSION...As of 1600 UTC, morning visible imagery showed initial
   ACCAS deepening along the cold front analyzed from western MN into
   northwest IA and eastern NE. Mid-level ascent associated with an
   upper trough over the western Dakotas was evident overspreading the
   front with an increase in cumuliform cloud structures on visible
   imagery. A prominent dry slot has also helped erode residual cloud
   cover from west to east, resulting in an increase in diurnal
   heating. The net result has been surface warming and reduction in
   residual inhibition on area model soundings. Sufficient
   boundary-layer moisture (dewpoints in the low to mid 60s F) in
   conjunction with the warming and ascent is supporting gradual
   destabilization with MLCAPE of 1000-2000 J/kg.

   As the upper trough and mid-level ascent continues eastward, flow
   aloft will strengthen. Initial thunderstorm development is likely by
   midday into early this afternoon over eastern NE and western IA.
   Morning RAOBs and the arrival of the upper trough will contribute to
   moderate deep-layer shear amidst veering wind profiles, supporting a
   mixed mode of supercells and line segments. Large buoyancy and cool
   mid-level temperatures suggest hail is likely with the initial
   storms. Low-level shear is also sufficient for a few tornadoes,
   especially with the more semi-discrete supercells.

   Initial frontal forcing is expected to result in scattered to
   widespread storm coverage. However, the cold front motion is
   relatively modest (080/15 kt) and should allow convection to move
   off the boundary and remain semi-discrete. With time, upscale growth
   into one or more linear clusters is likely. This would support a
   risk for damaging gust and a few embedded tornadoes. Given the
   expected increase in storm coverage within a favorable environment,
   a Tornado Watch is likely in the next couple of hours.

   ..Lyons/Guyer.. 04/23/2026

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

   ATTN...WFO...ARX...MPX...DMX...EAX...FSD...OAX...TOP...GID...

   LAT...LON   44439567 44879515 44899419 44519319 43609299 41859386
               40029539 39779672 39889736 40029759 40399753 41329710
               42259660 44089603 44439567 

   MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN