153  
FXUS63 KIWX 191035  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
635 AM EDT THU JUN 19 2025  
   
KEY MESSAGES  
 
- SHOWERS AND ISOLATED STORMS WILL EXIT THE AREA LATE THIS MORNING.  
 
- HEAT AND HUMIDITY WILL STEADILY BUILD FRIDAY THROUGH SUNDAY.  
HEAT INDICES SUNDAY AND MONDAY WILL BE AROUND 100F.  
 
- MAINLY DRY CONDITIONS ARE EXPECTED FROM THIS AFTERNOON THROUGH  
MONDAY.  
 
 
   
DISCUSSION  
 
ISSUED AT 254 AM EDT THU JUN 19 2025  
 
MIDLEVEL TROUGH AXIS REMAINS JUST UPSTREAM PER EARLY MORNING WATER  
VAPOR IMAGERY. RESULTANT CVA AND SOME ELEVATED DEFORMATION/FGEN  
(MAINLY OVER MI) WILL CONTINUE TO SUPPORT SCT SHOWERS OVER THE AREA  
THROUGH THE MORNING. WHILE FAR BETTER MOISTURE/INSTABILITY IS  
SHUNTED WELL TO OUR EAST BY NOW, MODELS SUGGEST COOL MIDLEVEL TEMPS  
AND SOME MARGINAL SURFACE HEATING BY MID-MORNING WILL BE ENOUGH TO  
SUPPORT SOME NON-ZERO CAPE AND A FEW ISOLATED STORMS. WILL THEREFORE  
ADD AN ISOLATED THUNDER MENTION BUT NO STRONG OR SEVERE STORMS ARE  
ANTICIPATED. ANY APPRECIABLE RAINFALL RATES WITHIN THE ISOLATED  
STORMS WILL LIKELY BE INSUFFICIENT TO CAUSE ANY FLOODING CONCERNS  
GIVEN QUICK STORM MOTION AND OVERALL LOW COVERAGE. TROUGH AXIS EXITS  
OUR EASTERN ZONES AROUND 18Z AND WILL SIGNAL THE END OF PRECIP  
CHANCES. SHOULD SEE A FAIR AMOUNT OF SUN BY LATE AFTERNOON BUT HIGHS  
WILL ONLY RECOVER INTO THE MID/UPPER 70S.  
 
THE BIG STORY IN THE LONG TERM REMAINS THE EXCESSIVE HEAT. AS  
TODAY'S TROUGH EXITS, A VERY STRONG AND LARGE UPPER RIDGE (500MB  
HEIGHTS VERY NEAR 600 DAM) WILL TAKE SHAPE OVER THE EASTERN CONUS.  
HIGHS STEADILY CLIMB OVER THE REGION FROM FRI-SUN AS THIS RIDGE  
TAKES SHAPE AND SW FLOW DEVELOPS FROM THE SOUTHERN PLAINS TO THE  
GREAT LAKES. MOST OF THIS PERIOD IS EXPECTED TO BE DRY THOUGH WILL  
HAVE TO KEEP AN EYE ON FRI NIGHT AS A FEW SHOWERS/STORMS COULD CLIP  
OUR FAR NORTH AS THE PRIMARY WARM FRONT LIFTS THROUGH MI. DRY  
CONDITIONS ARE ASSURED SAT-MON AS THIS RIDGE BUILDS. SUN AND MON  
CURRENTLY APPEAR TO BE THE HOTTEST DAYS WITH HIGHS IN THE MID 90S  
AND DEWPOINTS IN THE 70S YIELDING HEAT INDICES AROUND 100F. THERE IS  
SOME CONCERN THAT, DUE TO THE COOL SPRING/DELAYED START, THE LOCAL  
CROPS MAY NOT BE QUITE MATURE ENOUGH TO SUPPORT SOLID LOW-MID 70S  
DEWPOINTS NECESSARY TO YIELD HEAT INDICES OVER 100F. HOWEVER, THE  
WIDESPREAD 0.5-1" OF RAIN THAT FELL WILL CERTAINLY HELP IN THIS  
REGARD. HELD CLOSE TO NBM INITIALIZATION FOR NOW BUT THE 72-75F  
DEWPOINTS MAY NEED TO BE ADJUSTED DOWN SLIGHTLY IN FUTURE FORECASTS.  
GIVEN THIS UNCERTAINTY, IT REMAINS TOO EARLY FOR AN EXCESSIVE HEAT  
WATCH.  
 
THE NBM (HEAVILY INFLUENCED BY THE CONVECTION-LOVING GFS AND ITS  
ENSEMBLES) SUGGESTS RELIEF BY THE MIDDLE OF NEXT WEEK IN THE FORM OF  
A WEAK COLD FRONT AND SCT-NUM STORMS. THE ECMWF PAINTS A MUCH  
BLEAKER PICTURE SUGGESTING THE "COLD FRONT" REMAINS DRAPED OVER  
CENTRAL MI AND PRECIP NEVER QUITE REACHES OUR AREA (PERHAPS JUST  
SCRAPING OUR NORTHERN ZONES). LOOKING AT THE OVERALL PATTERN, THE  
ECMWF MAY BE CORRECT. EVEN ON THE DETERMINISTIC GFS THERE IS VERY  
LITTLE MID/UPPER SUPPORT FOR A FRONT TO PUSH FAR ENOUGH SOUTH TO  
SUPPORT ALL OF THAT CONVECTION THROUGHOUT THE OHIO VALLEY. THERE IS  
STILL PLENTY OF UNCERTAINTY THIS FAR OUT THOUGH AND DIDN'T MESS WITH  
NBM POP'S TOO MUCH. OF COURSE THE UNCERTAINTY IN POP'S SPILLS OVER  
INTO UNCERTAINTY WITH MAX TEMPS AND THE POTENTIAL EXTENSION OF EARLY-  
WEEK HEAT WAVE. STILL PLENTY OF TIME TO NAIL DOWN THOSE DETAILS  
THOUGH.  
 
 
   
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/  
 
ISSUED AT 624 AM EDT THU JUN 19 2025  
 
A DEEP SURFACE LOW WAS NORTH OF PORT HURON OVER FAR SOUTHEAST  
LOWER MICHIGAN AND WAS MOVING RAPIDLY NORTHEAST OVER LAKE HURON  
AT 10Z. THERE WERE STILL NUMEROUS SHOWERS UPSTREAM - SOUTHWEST  
OF THIS LOW OVER NORTHWEST INDIANA AND NORTHEAST IL. THE LOW  
WILL MOVE RAPIDLY EAST OUT OF THE AREA THIS AFTERNOON AND ALLOW  
CLEARING SKIES OVER NORTHERN INDIANA. A LARGE AREA OF IFR CLOUDS  
SHOULD LIFT AND RETREAT TO THE EAST OVER NORTHERN INDIANA  
BEFORE NOON.  
 
 
   
IWX WATCHES/WARNINGS/ADVISORIES  
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR LMZ043.  
 
 
 
 
 
DISCUSSION...AGD  
AVIATION...SKIPPER  
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