Mesoscale Discussion 1305
   NWS Storm Prediction Center Norman OK
   0504 PM CDT Tue Jul 21 2020

   Areas affected...central Illinois into west-central Indiana

   Concerning...Severe potential...Watch unlikely 

   Valid 212204Z - 212300Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A line of convection migrating eastward across the
   discussion area will pose a risk for isolated wind damage over the
   next couple hours or so.  A WW issuance is not anticipated, though
   convective trends are being monitored.

   DISCUSSION...Convection in central Illinois (near/south of KILX) has
   grown upscale into a linear segment while propagating eastward very
   near the I-55/US-51 corridor.  Briefly tornadic signatures developed
   on radar along the leading edge of this complex, which was likely
   tied to the propagation of the linear segment along an old outflow
   boundary left behind by earlier convection.  The storms are in an
   otherwise weakly sheared environment, but will propagate along a
   gradient of moderate to strong surface-based instability exceeding
   4000 J/kg MUCAPE across southeastern Illinois.  Continued
   propagation along the remnant outflow should contribute to an
   isolated damaging-wind and/or brief tornado threat over the next
   couple of hours.  The threat should remain too isolated to
   necessitate a WW issuance, although convective trends are being
   monitored.

   ..Cook/Grams.. 07/21/2020

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

   ATTN...WFO...IND...PAH...LOT...ILX...LSX...

   LAT...LON   40069004 40398932 40478791 40368705 39888666 39308671
               38758733 38578834 38538929 38768998 39179035 39609030
               40069004