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Storm Prediction Center Mesoscale Discussion 1230

Published Date and Time: 2026-06-21 15:36:00



Mesoscale Discussion 1230
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   Mesoscale Discussion 1230
   NWS Storm Prediction Center Norman OK
   0234 PM CDT Sun Jun 21 2026

   Areas affected...parts of south central/ southeastern Illinois and
   adjacent southwestern Indiana

   Concerning...Tornado Watch 363...

   Valid 211934Z - 212130Z

   The severe weather threat for Tornado Watch 363 continues.

   SUMMARY...The potential for one or two strong tornadoes may begin to
   maximize with evolving supercell structures across parts of
   southeastern Illinois, generally centered around the Effingham
   vicinity, by 4-6 PM CDT.

   DISCUSSION...Two-hourly surface pressure falls on the order of 2+ mb
   have become focused along a corridor from Litchfield through
   Effingham and Lawrenceville, southwestward toward Mt. Vernon,
   downstream of the remnant eastward migrating MCV.  Boundary-layer
   dew points are approaching 70F across this region, contributing to
   thermodynamic profiles with sizable buoyancy rooted near the
   surface.  Coupled with enlarging, clockwise-curved low-level
   hodographs beneath 30-50 south to southwesterly 850-500 mb flow
   overspreading the region, the environment appears to be coming
   increasingly conducive to the evolution of supercell structures
   posing a risk for tornadoes.  Given the potential for concentrating
   ambient vertical vorticity, coupled with potentially strong
   near-surface upward accelerations, a strong tornado or two appears
   possible.

   ..Kerr.. 06/21/2026

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

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

   LAT...LON   39038944 39348924 39448771 38838707 38238796 38488836
               38718883 39038944 


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