756  
ACUS11 KWNS 181611  
SWOMCD  
SPC MCD 181610  
ILZ000-WIZ000-IAZ000-181745-  
 
MESOSCALE DISCUSSION 1983  
NWS STORM PREDICTION CENTER NORMAN OK  
1110 AM CDT MON AUG 18 2025  
 
AREAS AFFECTED...NORTHERN ILLINOIS AND SOUTHERN WISCONSIN  
 
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE  
 
VALID 181610Z - 181745Z  
 
PROBABILITY OF WATCH ISSUANCE...60 PERCENT  
 
SUMMARY...THE DAMAGING WIND THREAT WILL INCREASE ACROSS NORTHERN  
ILLINOIS AND SOUTHERN WISCONSIN THIS AFTERNOON.  
 
DISCUSSION...AN OUTFLOW BOUNDARY FROM OVERNIGHT STORMS CONTINUES TO  
MOVE EAST ACROSS SOUTHERN WISCONSIN, FAR EASTERN IOWA, AND  
NORTHWESTERN ILLINOIS. STORMS HAVE STARTED TO STRENGTHEN ALONG THIS  
BOUNDARY AS THE BOUNDARY LAYER DESTABILIZES. SPC MESOANALYSIS  
INDICATES SOME WEAK INHIBITION REMAINS AHEAD OF STORMS, BUT IS  
MOSTLY ERODED FARTHER EAST ACROSS SOUTHERN WISCONSIN AND NORTHERN  
ILLINOIS WHERE TEMPERATURES HAVE WARMED INTO THE LOW TO MID 80S.  
THEREFORE, EXPECT ADDITIONAL STRENGTHENING OF THE UPDRAFTS AS THIS  
LINE MOVES EAST. AROUND 35 KNOTS OF EFFECTIVE SHEAR (PER MKX VWP)  
SHOULD BE SUFFICIENT TO SUSTAIN SOME DAMAGING WIND THREAT FROM THESE  
STORMS AS THEY MOVE EAST. A SEVERE THUNDERSTORM WATCH MAY NEED TO BE  
ISSUED BY EARLY AFTERNOON IF STORM INTENSITY/COVERAGE INCREASES AS  
ANTICIPATED.  
 
..BENTLEY/MOSIER.. 08/18/2025  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...LOT...ILX...MKX...DVN...  
 
LAT...LON 41099073 41539031 42179019 42819014 43329016 43518894  
43278777 42608770 42138757 41648753 40988759 40818877  
40918984 41109050 41099073  
 
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH  
MOST PROBABLE PEAK WIND GUST...55-70 MPH  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page