Storm Prediction Center Mesoscale Discussion 565

   Mesoscale Discussion 0565
   NWS Storm Prediction Center Norman OK
   0736 AM CDT Mon Apr 27 2026

   Areas affected...Eastern/northern Missouri and southern Illinois

   Concerning...Severe Thunderstorm Watch 156...157...

   Valid 271236Z - 271400Z

   The severe weather threat for Severe Thunderstorm Watch 156, 157
   continues.

   SUMMARY...Elevated storms will persist through mid morning into west
   central and southern Illinois with the threat for large hail.  A
   separate MCS will spread eastward from WW #156 into WW #157.

   DISCUSSION...Elevated storms continue in a zone of low-level warm
   advection on the nose of a 50 kt low-level jet.  This area has been
   near the east edge of the destabilization aloft overnight, and this
   trend should continue with storms into western and southern IL,
   where large hail of 1-1.75 inches in diameter will be the main
   threat.

   Farther west, earlier supercells in KS/MO have evolved into multiple
   line segments with occasional mesovortices.  The strongest portions
   of the line have been more north-south oriented, orthogonal to the
   deep-layer shear vectors and with substantial streamwise vorticity
   in the low levels.  Embedded circulations will continue to be
   possible, though the storms may slightly out pace northward
   expansion of the surface warm sector and associated surface-based
   buoyancy.  An isolated mesovortex tornado could occur, but the
   primary threats will remain damaging winds and large hail in the
   near term.

   ..Thompson.. 04/27/2026

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

   ATTN...WFO...PAH...ILX...LSX...SGF...EAX...

   LAT...LON   38119068 38389265 38589297 39399222 39959206 40059126
               40009095 39609044 38848874 38238800 36958860 36868917
               38119068 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN