054  
ACUS11 KWNS 170106  
SWOMCD  
SPC MCD 170106  
ILZ000-WIZ000-IAZ000-170230-  
 
MESOSCALE DISCUSSION 1969  
NWS STORM PREDICTION CENTER NORMAN OK  
0806 PM CDT SAT AUG 16 2025  
 
AREAS AFFECTED...PORTIONS OF NORTHEASTERN IOWA SOUTHWEST WISCONSIN  
AND NORTHERN ILLINOIS  
 
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY  
 
VALID 170106Z - 170230Z  
 
PROBABILITY OF WATCH ISSUANCE...20 PERCENT  
 
SUMMARY...STORMS FORMING ALONG A TRAILING OUTFLOW BOUNDARY MAY  
REMAIN CAPABLE OF SPORADIC HAIL AND OCCASIONAL STRONG WIND GUSTS FOR  
A FEW HOURS THIS EVENING.  
 
DISCUSSION...AS OF 01 UTC, REGIONAL RADAR IMAGERY SHOWED SEVERAL  
CLUSTERS OF STORMS HAD REDEVELOPED ALONG A TRAILING OUTFLOW BOUNDARY  
FROM PRIOR CONVECTION ACROSS PORTIONS OF NORTHERN IL, EASTERN IA AND  
SOUTHWESTERN WI. SEVERAL OF THESE STORMS HAVE SHOWN PERIODS OF  
HIGHER INTENSITY WITH REPORTS OF HAIL OVER THE LAST HOUR. THIS  
THREAT SHOULD CONTINUE WITH OCCASIONAL HAIL OR DAMAGING GUSTS AS THE  
AIR MASS ALONG AND SOUTH OF THE OUTFLOW REMAINS VERY UNSTABLE WITH  
4000-5000 J/KG OF MUCAPE. VERTICAL SHEAR, WHILE NOT OVERLY STRONG  
(25-35 KT 0-6KM AGL), IS SUFFICIENT FOR A MIXED CONVECTIVE MODE OF  
MULTICELL CLUSTERS AND TRANSIENT SUPERCELL STRUCTURES NEAR THE  
BOUNDARY.  
 
THE TENDENCY FOR DEVELOPING STORMS TO MOVE EASTWARD TOWARD WEAKER  
BUOYANCY SUGGESTS INTENSIFICATION OF INDIVIDUAL CELLS SHOULD BE  
RELATIVELY BRIEF. ADDITIONALLY, THE STRONGEST VERTICAL SHEAR REMAINS  
DISPLACED FARTHER NORTH WHICH SHOULD KEEP OVERALL ORGANIZATION  
LIMITED. A WW IS UNLIKELY GIVEN THE LACK OF A MORE FOCUSED/SUSTAINED  
SEVERE RISK, BUT OCCASIONAL HAIL AND A DAMAGING GUST ARE POSSIBLE.  
 
..LYONS/SMITH.. 08/17/2025  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...LOT...MKX...DVN...ARX...  
 
LAT...LON 41308897 41728984 42259068 42849174 43259169 43279015  
42868903 42028796 41488801 41278823 41308897  
 
MOST PROBABLE PEAK WIND GUST...55-70 MPH  
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page