646
ACUS11 KWNS 162145
SWOMCD
SPC MCD 162144
INZ000-ILZ000-162245-
MESOSCALE DISCUSSION 1967
NWS STORM PREDICTION CENTER NORMAN OK
0444 PM CDT SAT AUG 16 2025
AREAS AFFECTED...NORTHERN ILLINOIS AND NORTHWEST INDIANA
CONCERNING...SEVERE THUNDERSTORM WATCH 596...
VALID 162144Z - 162245Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 596
CONTINUES.
SUMMARY...A CLUSTER OF SEVERE STORMS WILL MOVE SOUTHEASTWARD OVER
THE CHICAGO METRO THROUGH THE NEXT 1-2 HOURS. DAMAGING GUSTS AND
SOME HAIL ARE LIKELY.
DISCUSSION...AS OF 2145 UTC, LOCAL RADAR SHOWED A CLUSTER OF SEVERE
THUNDERSTORMS ONGOING OVER PORTIONS OF NORTHERN IL. OVER THE LAST
HALF HOUR, SEVERAL REPORT OF SEVERE WIND GUSTS AND 1-1.5 INCH HAIL
HAVE OCCURRED WITH THESE CELLS. CONTINUED INTENSIFICATION APPEARS
LIKELY AS THESE CELLS TRACK SOUTHEASTWARD AT 30 KT ALONG A BUOYANCY
GRADIENT OF 3000-4000 J/KG OF MLCAPE AND LOCAL LAKE BREEZE
BOUNDARIES. THESE CELLS WILL CONTINUE ACROSS THE CHICAGO METRO
THROUGH THE NEXT 1-2 HOURS WITH DAMAGING GUSTS OF 60-70 MPH AND HAIL
UP TO THE SIZE OF GOLF BALLS LIKELY.
AS STORMS EXIT NORTHERN IL INTO NORTHWEST IN, SOME LOSS OF
ORGANIZATION IS EXPECTED AS VERTICAL SHEAR DECREASES TO THE SOUTH.
HOWEVER, LARGE BUOYANCY AND THE STRONG COLD POOL SHOULD CONTINUE TO
SUPPORT SOME SEVERE RISK OVER THE NEXT COUPLE OF HOURS.
..LYONS.. 08/16/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...IWX...LOT...
LAT...LON 42008899 42228784 41938744 41588687 41238688 40968732
40948804 41338867 41368876 42008899
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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