561  
FXUS63 KIWX 082341  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
741 PM EDT TUE JUL 8 2025  
   
KEY MESSAGES
 
 
- SEASONABLY WARM & HUMID CONDITIONS WILL PERSIST, WITH DAILY  
MAXIMUM HEAT INDEX VALUES IN THE UPPER 80S TO AROUND 90  
DEGREES.  
 
- AN ACTIVE WEATHER PATTERN WILL RETURN ON WEDNESDAY, RESULTING  
IN FREQUENT FOR SHOWERS AND THUNDERSTORMS OVER THE NEXT  
SEVERAL DAYS.  
 
- SEVERE WEATHER CHANCES ARE EXPECTED TO REMAIN LOW. HOWEVER,  
LOCALLY HEAVY RAINFALL MAY BECOME A CONCERN THIS WEEKEND.  
 

 
   
DISCUSSION
 
 
ISSUED AT 130 PM EDT TUE JUL 8 2025  
 
AN ACTIVE WEATHER PATTERN WILL RETURN TO THE AREA OVER THE NEXT  
SEVERAL DAYS WITH THE PASSAGE OF NUMEROUS MID AND UPPER-LEVEL  
DISTURBANCES. A WELL-DEFINED SHORT WAVE TROUGH AXIS WILL  
TRAVERSE THE AREA THIS AFTERNOON AND EVENING, WITH NUMEROUS  
SHOWERS AND STORMS LIKELY DEVELOPING UPSTREAM ACROSS IL. MOST  
HIGH-RES MODELS SUGGEST THIS ACTIVITY SHOULD DISSIPATE OR AT  
LEAST WEAKEN SIGNIFICANTLY PRIOR TO REACHING OUR WESTERN ZONES  
AFTER 00Z W/ THE LOSS OF DIURNAL INSTABILITY, BUT NONETHELESS A  
FEW LIGHT SHOWERS WILL REMAIN POSSIBLE THROUGH THE NIGHT ACROSS  
THE ENTIRE CWA. ISOLATED TO WIDELY SCATTERED STORMS WILL BE A  
POSSIBILITY AGAIN DURING THE LATE AFTERNOON AND EARLY EVENING  
HOURS ON WEDNESDAY WITH A SUBTLE RIPPLE IN THE FLOW / WEAK VORT  
MAX ON THE BACK SIDE OF THE AFOREMENTIONED TROUGH. AFTER A BRIEF  
LULL DURING THE DAY ON THURSDAY, MODELS SUGGEST A RATHER COMPLEX  
PATTERN EVOLUTION W/ TWO HIGHLY ENERGETIC SOUTHERN AND NORTHERN  
STREAM DISTURBANCES INTERACTING OVER THE CENTRAL PLAINS. WHILE  
THE EXACT EVOLUTION OF THIS PATTERN REMAINS A BIT MUDDY AT THIS  
TIME, PRECIPITATION CHANCES SHOULD INCREASE MARKEDLY ESPECIALLY  
FROM FRIDAY NIGHT THROUGH SATURDAY. FORECAST VERTICAL PROFILES  
APPEAR EXTREMELY MOIST WITH VERY TALL/SKINNY CAPE PROFILES,  
SUPPORTING A THREAT FOR LOCALLY HEAVY RAINFALL WHICH IS  
HIGHLIGHTED IN THE LATEST WPC DAYS 4/5 EXCESSIVE RAINFALL  
OUTLOOKS. AT THIS TIME, THIS DOES NOT APPEAR TO BE A WIDESPREAD  
HEAVY RAIN EVENT THOUGH W/ THE LATEST NBM SPECTRUM SUGGESTING  
ONLY AROUND A 20% CHANCE OF EXCEEDING 0.5 INCH QPF ACROSS MUCH  
OF THE AREA DESPITE A FEW DETERMINISTIC RUNS HINTING AT MUCH  
MORE ROBUST TOTALS. OTHERWISE, SEASONABLY HOT AND HUMID  
CONDITIONS WILL PERSIST W/ THE MORE SUBSTANTIAL HUMIDITY  
ARRIVING IN TIME FOR THE WEEKEND WHICH MAY HELP PUSH HEAT  
INDICES INTO THE LOWER 90S.  
 

 
   
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
 
 
ISSUED AT 740 PM EDT TUE JUL 8 2025  
 
HUMIDITY INCREASES BETWEEN TONIGHT AND WEDNESDAY AS A MID LEVEL  
TROUGH TRAVERSES THROUGH OUR AREA. THIS ALLOWS FOR AN INCREASED  
CHANCE FOR SHOWERS AND STORMS, ESPECIALLY BY THE TIME WE GET TO  
WEDNESDAY AFTERNOON. THE HRRR SHOWS SOME CHANCE OF SHOWERS/STORMS BY  
15Z WED AND SO WILL USE A PROB30 FOR THAT TIME PERIOD. WILL  
ALSO USE A PROB30 GROUP FOR THE AFTERNOON AND BOTH OF THESE  
GROUPS WILL HAVE MVFR FLIGHT CONDITIONS FOR NOW. WIND-WISE,  
SOUTHWEST WINDS TONIGHT BECOME MORE WESTERLY AND NORTHWESTERLY  
AS THE SHORTWAVE MOVES THROUGH THE AREA WEDNESDAY. SPEEDS  
GENERALLY STAY BELOW 10 KTS.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...NONE.  
 

 
 

 
 
DISCUSSION...HAMMER  
AVIATION...ROLLER  
 
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