141  
ACUS11 KWNS 131906  
SWOMCD  
SPC MCD 131906  
OHZ000-MIZ000-INZ000-ILZ000-131930-  
 
MESOSCALE DISCUSSION 0397  
NWS STORM PREDICTION CENTER NORMAN OK  
0206 PM CDT MON APR 13 2026  
 
AREAS AFFECTED...PORTIONS OF NORTHEASTERN ILLINOIS INTO NORTHERN  
INDIANA AND EXTREME SOUTHERN LOWER MICHIGAN  
 
CONCERNING...SEVERE POTENTIAL...WATCH NEEDED SOON  
 
VALID 131906Z - 131930Z  
 
PROBABILITY OF WATCH ISSUANCE...95 PERCENT  
 
SUMMARY...THE SEVERE THREAT IS INCREASING, WITH A WW ISSUANCE  
IMPENDING. SEVERE HAIL APPEARS TO BE THE MAIN THREAT, THOUGH A  
COUPLE OF DAMAGING GUSTS ARE ALSO POSSIBLE.  
 
DISCUSSION...ELEVATED CONVECTION, WHICH HAS BEEN OSCILLATING IN  
INTENSITY WITHIN A LOW-LEVEL WAA ADVECTION REGIME, HAS RECENTLY  
SHOWN AN UPTICK IN INTENSITY, WITH 1 INCH DIAMETER HAIL RECENTLY  
REPORTED. THESE STORMS ARE MOVING OVER A HEATED AIRMASS, WITH  
SURFACE TEMPERATURES WARMING INTO THE 80S F. GIVEN BOUNDARY LAYER  
GROWTH, THESE STORMS ARE LIKELY ROOTING INTO THE BOUNDARY LAYER,  
WHERE 1500 J/KG MLCAPE IS PRESENT. GIVEN 30+ KTS OF EFFECTIVE BULK  
SHEAR, SURFACE-BASED SUPERCELL DEVELOPMENT IS LIKELY UNDERWAY. THE  
STRONGEST STORMS WILL SUPPORT A SEVERE HAIL THREAT OVER THE NEXT FEW  
HOURS, THOUGH A DAMAGING GUST OR TWO IS POSSIBLE. A TORNADO CANNOT  
BE COMPLETELY RULED OUT. GIVEN THE RECENT UPTICK IN STORM INTENSITY,  
A SEVERE THUNDERSTORM WATCH WILL BE ISSUED MOMENTARILY.  
 
..SQUITIERI/HART.. 04/13/2026  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT  
 
ATTN...WFO...IWX...IND...LOT...  
 
LAT...LON 41448883 41908707 42028574 41938492 41618460 41168467  
40798527 40668612 40608701 40608766 40738846 41448883  
 
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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