873  
FXUS63 KIWX 102330  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
730 PM EDT THU JUL 10 2025  
   
KEY MESSAGES
 
 
- SEVERAL ROUNDS OF RAIN/STORMS ARE POSSIBLE OVER THE NEXT FEW  
DAYS, MAINLY FRIDAY MORNING AND THEN AGAIN LATE SATURDAY INTO  
SUNDAY MORNING.  
 
- A FEW STORMS COULD BE STRONG TO SEVERE OVER THE WEEKEND, WITH A  
MARGINAL RISK FOR SEVERE WEATHER.  
 
- ISOLATED INSTANCES OF FLOODING ARE POSSIBLE SATURDAY NIGHT  
INTO SUNDAY MORNING.  
 
- HOT AND HUMID FRIDAY AND SATURDAY WITH HEAT INDICES IN THE  
MID TO UPPER 90S.  
 
- MAINLY DRY WITH CONTINUED HEAT AND HUMIDITY INTO EARLY NEXT  
WEEK.  
 

 
   
DISCUSSION
 
 
ISSUED AT 255 PM EDT THU JUL 10 2025  
 
SEVERAL ROUNDS OF SHOWERS AND STORMS WILL BE POSSIBLE THROUGH THE  
WEEKEND. CONFIDENCE IS LOW TO MEDIUM IN HOW THE PATTERN EVOLVES IN  
THE NEXT 12-24 HOURS DUE TO SEVERAL FACTORS. AN MCS WILL MOVE  
THROUGH AND DECAY ACROSS IOWA AND ILLINOIS OVERNIGHT INTO EARLY  
FRIDAY MORNING. CAMS ARE SPLIT ON HOW THIS CONVECTION EVOLVES; THE  
ATMOSPHERE SHOULD REMAIN CAPPED BUT IT IS POSSIBLE SOME OF THIS  
REMNANT CONVECTION SURVIVES AND MAKES IT INTO OUR AREA FRIDAY  
MORNING, ESPECIALLY ACROSS NORTHWEST INDIANA AND SOUTHWEST LOWER  
MICHIGAN. HOW THE MORNING MCS EVOLVES WILL INFLUENCE HOW THE REST OF  
FRIDAY GOES...CAMS TRY TO REINVIGORATE CONVECTION IN ILLINOIS ALONG  
ANY REMNANT OUTFLOW BOUNDARIES, BUT EXACTLY WHERE AND WHEN  
CONVECTION WILL DEVELOP REMAINS HIGHLY DEPENDENT ON IF/WHERE ANY  
OUTFLOWS SET UP. THE CAP SHOULD HOLD OVER OUR AREA FRIDAY, BUT I  
CAN'T RULE OUT A FEW ISOLATED SHOWERS OR STORMS TOMORROW  
AFTERNOON/EVENING. BECAUSE TOMORROW'S FORECAST IS OF LOW CONFIDENCE,  
HAVE LEFT POPS CAPPED AT 40% FOR THE MORNING AND 20% FOR THE  
AFTERNOON. SUBSEQUENT SHIFTS CAN ADJUST AS NEEDED IF CONFIDENCE WERE  
TO INCREASE FOR A PARTICULAR TIMEFRAME (ESPECIALLY THE  
AFTERNOON/EVENING TIMEFRAME). SPC DID UPGRADE AREAS NORTH OF US 30  
INTO A SLIGHT RISK (LEVEL 2 OF 5) FOR FRIDAY ALTHOUGH CONFIDENCE IS  
VERY LOW IN ANY STORMS REACHING SEVERE CRITERIA, UNLESS STORMS ARE  
ABLE TO DEVELOP ALONG A REMNANT OUTFLOW BOUNDARY.  
 
HEAT AND HUMIDITY BUILD ON FRIDAY INTO SATURDAY, SETTING THE  
STAGE FOR ANOTHER ROUND OF RAIN/STORMS OVER THE WEEKEND AS A  
COLD FRONT COMES THROUGH. INCREASING SOUTHERLY LOW LEVEL FLOW  
AND WAA WILL RESULT IN HIGH TEMPERATURES IN THE UPPER 80S TO LOW  
90S AND DEWPOINTS IN THE MID 70S BY SATURDAY, WHICH WILL LEAD  
TO PEAK HEAT INDICES IN THE MID TO UPPER 90S. A COLD FRONT,  
AIDED BY A 500 MB SHORTWAVE PIVOTING THROUGH, WILL BRING CHANCES  
FOR RAIN/STORMS TO THE AREA LATE SATURDAY AFTERNOON THROUGH  
SUNDAY MORNING. THE CAP WILL LIKELY HOLD UNTIL THE LATTER HALF  
OF THE DAY, BUT HOT AND HUMID CONDITIONS SHOULD ALLOW FOR  
DESTABILIZATION TO OCCUR BY THE AFTERNOON AND EVENING. WITH  
AMPLE INSTABILITY (2500-3000 J/KG SB CAPE) BUT UNIDIRECTIONAL  
FLOW AT THE SURFACE AND ALOFT, A FEW STORMS MAY BE STRONG TO  
SEVERE BUT WIDESPREAD SEVERE WEATHER IS NOT EXPECTED OVER THE  
WEEKEND AT THIS TIME. ONCE AGAIN, SPC HAS THE AREA IN A MARGINAL  
RISK (LEVEL 1 OF 5) ON SATURDAY. NAM SOUNDINGS SHOW INVERTED V  
PROFILES, WHICH WOULD SUGGEST GUSTY TO DAMAGING WINDS WOULD BE  
THE MAIN HAZARD. SIGNALS FOR HEAVY RAINFALL ARE ALSO THERE FOR  
SATURDAY EVENING INTO SUNDAY MORNING. GIVEN THAT THE HEAVIEST  
RAIN/STORMS MAY MOVE THROUGH OVERNIGHT WITH WEAK SOUTHWEST FLOW  
PARALLEL TO THE FRONT AND PWATS AROUND 2", FLOODING POTENTIAL  
MAY NEED TO BE MONITORED SATURDAY NIGHT INTO SUNDAY. WPC DOES  
HAVE MUCH OF OUR FORECAST AREA IN A MARGINAL RISK (LEVEL 1 OF 4)  
FOR ISOLATED INSTANCES OF FLASH FLOODING ON SATURDAY AND  
SUNDAY.  
 
A WEAKLY AMPLIFIED UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE BUILD  
ACROSS THE GREAT LAKES REGION INTO EARLY NEXT WEEK, BRINGING DRY  
CONDITIONS LATER SUNDAY THROUGH TUESDAY. CHANCES FOR DIURNALLY  
DRIVEN SHOWERS AND STORMS WILL PERSIST EACH DAY, BUT CHANCES ARE  
FAIRLY LOW (20% OR LESS). HOT AND HUMID CONDITIONS PERSIST UNDER THE  
UPPER LEVEL RIDGE WITH HIGHS NEAR 90 DEGREES UNTIL MIDWEEK.  
 

 
   
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
 
 
ISSUED AT 720 PM EDT THU JUL 10 2025  
 
A MESOLOW OVER MN/IA WILL PUSH EAST TO SOUTHEAST OVERNIGHT AND  
SOME CONVECTIVE ACTIVITY ALREADY HAD DEVELOPED OVER SOUTHERN  
WI/NORTHERN IL. THIS ACTIVITY CONTINUES TO PUSH EASTWARD AND AS  
IT DECAYS THERE IS THE POTENTIAL FOR SOME SHOWERS AND PERHAPS A  
THUNDERSTORM FOR KSBN AROUND 10Z FRI. AT THIS TIME THERE IS LOW  
CONFIDENCE ON THE THUNDERSTORM POTENTIAL SO DID OPT TO LEAVE  
MENTION OUT OF THE TAF BUT DID KEEP IN THE SHOWERS FOR KSBN AS  
IT IS LIKELY SOME SHOWERS WILL SURVIVE AND BRING MVFR VSBYS.  
WILL BE MONITORING TO SEE IF THIS ACTIVITY MAY COME IN A BIT  
QUICKER AND WILL UPDATE AS NEEDED. OTHERWISE, VFR CONDITIONS  
WILL PREVAIL.  
 

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

 
 

 
 
DISCUSSION...JOHNSON  
AVIATION...ANDERSEN  
 
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