420  
FXUS63 KIWX 132304  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
704 PM EDT TUE MAY 13 2025  
   
KEY MESSAGES  
 
- SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THIS AFTERNOON, AND  
AGAIN WEDNESDAY AFTERNOON.  
 
- VERY WARM ON THURSDAY WITH HIGHS WELL INTO THE 80S.  
 
- WHILE THE DAYTIME WILL BE PRIMARILY DRY THURSDAY, THERE IS A  
CHANCE FOR THUNDERSTORMS THURSDAY EVENING AND OVERNIGHT, SOME  
OF WHICH MAY BE SEVERE.  
 
 
   
DISCUSSION  
 
ISSUED AT 220 PM EDT TUE MAY 13 2025  
 
UPPER LOW CENTER OVER THE WESTERN TN VALLEY WILL FINALLY GET A PUSH  
NORTH INTO THE OH VALLEY AND SOUTHERN GREAT LAKES TONIGHT INTO  
WEDNESDAY IN RESPONSE TO A DEEP UPPER TROUGH EDGING EAST TOWARD THE  
ROCKIES. THIS SYSTEM WILL CONTINUE TO GENERATE ISOLATED TO SCATTERED  
SHOWERS AND STORMS (MAINLY DIURNAL) THANKS TO A MOIST COLUMN THROUGH  
MUCH OF THE TROPOSPHERE AND JUST ENOUGH DIURNAL HEATING, WITH THE  
GREATEST COVERAGE LIKELY FOCUSED NEAR SMALL SCALE VORT LOBES  
ROTATING AROUND THE UPPER LOW. OVERALL WEAK DYNAMICS, FLOW AND  
INSTABILITY PRECLUDES A SEVERE WX RISK WITH LIGHTNING, BRIEF  
DOWNPOURS AND COLD AIR FUNNELS POSSIBLE WITH HEAVIER SHOWERS EACH  
AFTERNOON.  
 
THE ROCKIES UPPER LOW WILL EJECT INTO THE NORTHERN PLAINS AND UPPER  
MIDWEST THURSDAY INTO THURSDAY NIGHT WITH AN ASSOCIATED STRONG SFC  
LOW EMERGING OVER MN BY FRIDAY MORNING PER LATEST GUIDANCE. A  
LEADING WARM FRONT AND LOW LEVEL THETA-E RIDGE ADVECT INTO THE LOCAL  
AREA ON THURSDAY WITH WARM TEMPS (NEAR RECORDS) AND A CONDITIONAL  
SEVERE RISK THURSDAY NIGHT. PROGGED SHEAR/INSTABILITY PROFILES CHECK  
THE BOX FOR POTENTIAL DEEP/SEVERE CONVECTION, HOWEVER, DELAYED  
FORCING AND WHAT LOOKS TO BE A VERY WARM EML BASE MAY KEEP A LID ON  
ORGANIZED CONVECTION ALONG AN INCOMING PRE-FRONTAL TROUGH OR  
CONVECTIVE OUTFLOW.  
 
HEIGHT FALLS EVENTUALLY SLIDE EAST THROUGH THE GREAT LAKES FRIDAY  
INTO SATURDAY WITH THE UPCOMING WEEKEND TRENDING COOLER, DRY AND  
BREEZY IN RESPONSE TO THE SUPPRESSION. COULD SEE ANOTHER FRONTAL  
WAVE DRIVE A CONVECTIVE COMPLEX THROUGH THE REGION FRIDAY PM IN THIS  
TRANSITION, THOUGH THE BULK OF GUIDANCE CONTINUES TO FAVOR AREAS OFF  
THE SOUTH FOR MORE ORGANIZED CONVECTION CHANCES. THURSDAY NIGHT'S  
ACTIVITY, OR LACK THEREOF, WILL DICTATE THE TIMING/TRACK OF FRIDAY'S  
POTENTIAL CONVECTIVE SYSTEM.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/  
 
ISSUED AT 651 PM EDT TUE MAY 13 2025  
 
WITH THE VERY MOIST AIRMASS IN PLACE VERY LOW CIGS AND PERHAPS  
DEVELOPMENT OF PATCHY FOG OVERNIGHT WILL BE THE MAIN IMPACTS.  
VFR/MVFR CONDITIONS EARLY ON THIS EVENING WILL DEGRADE THROUGH  
THE OVERNIGHT HOURS WITH IFR AND POTENTIALLY LIFR CONDITIONS  
AFTER 08Z WED FOR KSBN. WILL NEED TO KEEP AN EYE ON THE TRENDS AS  
KFWA LOOKS TO DROP TO IFR IN CIGS AFTER 06Z WED BUT CONFIDENCE  
OF DROPPING INTO LIFR WAS NOT AS HIGH. HOWEVER, WITH THE VERY  
MOIST CONDITIONS IS CERTAINLY NOT OUT OF THE QUESTION THAT  
EITHER THE CIGS OR VSBYS DROP SLIGHTLY FURTHER INTO THE LIFR  
CATEGORY. CIGS LOOK TO IMPROVE TO MVFR AFTER 15-16Z FOR BOTH TAF  
SITES ALONG WITH INCREASED CHANCES OF RAIN SHOWERS. AFTERNOON  
THUNDER AND LIGHT RAIN WILL ONCE AGAIN RE-DEVELOP FOR BOTH SITES  
AFTER 20Z WED.  
 
 
   
IWX WATCHES/WARNINGS/ADVISORIES  
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...ANDERSEN  
AVIATION...FRAZIER  
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