978
ACUS11 KWNS 211934
SWOMCD
SPC MCD 211934
INZ000-ILZ000-212130-
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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