466
ACUS11 KWNS 271725
SWOMCD
SPC MCD 271724
INZ000-ILZ000-271900-
MESOSCALE DISCUSSION 1762
NWS STORM PREDICTION CENTER NORMAN OK
1224 PM CDT MON JUL 27 2026
AREAS AFFECTED...NORTHEAST IL/NORTHWEST IN
CONCERNING...SEVERE THUNDERSTORM WATCH 520...
VALID 271724Z - 271900Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 520
CONTINUES.
SUMMARY...A FAVORABLE ENVIRONMENT SUPPORTING LARGE TO VERY LARGE
HAIL AND A TORNADO RISK WILL DEVELOP ACROSS PORTIONS OF NORTHEAST IL
INTO NORTHWEST IN OVER THE NEXT 1-2 HOURS.
DISCUSSION...A SUPERCELL LOCATED OVER NORTHEAST IL WILL DEVELOP
SOUTH/SOUTHEAST ACROSS THE SOUTHERN GREATER CHICAGO METRO VICINITY.
THE DOWNSTREAM AIRMASS IS VERY MOIST (MID/UPPER 70S DEWPOINTS) AND
UNSTABLE (3000-4000 J/KG MLCAPE). FAVORABLE VERTICAL SHEAR WITH 50+
KT EFFECTIVE SHEAR MAGNITUDES AND 0-1 SRH NEAR 125 M2/S2 IS NOTED
FROM THE KLOT VWP. EFFECTIVE STP VALUES HAVE INCREASED TO 3-5 AS
WELL. THIS ENVIRONMENT WILL CONTINUE TO SUPPORT SUPERCELL STRUCTURES
WITH A CONTINUED RISK FOR VERY LARGE HAIL TO AROUND 2.5 INCHES,
STRONG WIND GUSTS, AND POSSIBLY A STRONG TORNADO OVER THE NEXT 1-2
HOURS.
..LEITMAN.. 07/27/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...LOT...
LAT...LON 42018782 41528726 41138721 40998753 41038799 41228829
41718827 41928825 42058811 42018782
MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
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