551
ACUS11 KWNS 111929
SWOMCD
SPC MCD 111928
INZ000-ILZ000-112130-
MESOSCALE DISCUSSION 1930
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT TUE AUG 11 2026
AREAS AFFECTED...EAST-CENTRAL ILLINOIS INTO WEST-CENTRAL AND
SOUTHERN INDIANA
CONCERNING...SEVERE THUNDERSTORM WATCH 565...
VALID 111928Z - 112130Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 565
CONTINUES.
SUMMARY...DAMAGING WIND POTENTIAL MAY INCREASE WITH MORE RECENT
THUNDERSTORM DEVELOPMENT, WHICH WOULD POTENTIALLY REQUIRE AN
EXTENSION OF THE WATCH INTO PORTIONS OF SOUTHWEST INDIANA.
DISCUSSION...A WEST-TO-EAST-ORIENTED BAND OF THUNDERSTORMS HAS
RECENTLY INTENSIFIED ACROSS PORTIONS OF EAST-CENTRAL IL INTO
WEST-CENTRAL IN, TO THE NORTH OF AN OUTFLOW BOUNDARY FROM EARLIER
CONVECTION. THE 18Z ILX SOUNDING IS LIKELY REPRESENTATIVE OF THE
INFLOW ENVIRONMENT WITH STEEP MID-LEVEL LAPSE RATES AND A MOIST
BOUNDARY LAYER YIELDING MLCAPE OF 2000-2500 J/KG. THE CURRENT STORMS
MIGHT STILL BE SLIGHTLY ELEVATED ATOP A SHALLOW SURFACE INVERSION.
HOWEVER, A CONTINUED STORM MOTION TOWARD THE MORE UNSTABLE
ENVIRONMENT SHOULD SUPPORT A TRANSITION TO SURFACE-BASED UPDRAFTS
WITH AN INCREASING THREAT FOR DAMAGING WIND GUSTS AS THE ATTENDING
COLD POOL MATURES. PRIOR TO THAT, ISOLATED OCCURRENCES OF SEVERE
HAIL ARE POSSIBLE.
THE SEVERE THREAT IS EXPECTED TO LARGELY SPREAD SOUTHEAST INTO THE
WATCH AREA OVER THE NEXT HOUR, SO AN ADDITIONAL WATCH TO THE WEST IN
IL IS NOT CURRENTLY ANTICIPATED. HOWEVER, THE CURRENT WATCH MAY NEED
TO BE LOCALLY EXTENDED INTO SOUTHWEST IN.
..MEAD.. 08/11/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...LMK...IWX...IND...LOT...ILX...
LAT...LON 39828835 40558847 40708746 40588685 39728618 39098568
38728585 38788656 39058739 39478786 39828835
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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