416
FXUS63 KIWX 291719
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
119 PM EDT MON JUN 29 2026
KEY MESSAGES
- EXTREME HEAT WARNING IS IN EFFECT THROUGH THURSDAY EVENING
FOR AN EXTENDED PERIOD OF HIGH HEAT INDICES AND LIMITED
NIGHTTIME COOLING.
- HEAT MAY REMAIN A CONCERN FRIDAY, BUT CHANCES FOR SHOWERS AND
THUNDERSTORMS BEGIN TO INCREASE RESULTING IN LOWER CONFIDENCE
ON THE AMOUNT OF IMPACTS.
UPDATE
ISSUED AT 955 AM EDT MON JUN 29 2026
SFC WARM FRONT (ESSENTIALLY SHIFT OF WINDS TO SW AND A
PRONOUNCED INCREASE IN DEWPOINTS) WAS LOCATED FROM GRR SE TO
NEAR LIMA, OH. THE SHOWERS THAT WERE AHEAD OF THIS EARLIER HAVE
DISSIPATED. THE FRONT WILL CLEAR THE AREA OVER THE NEXT COUPLE
OF HOURS WITH 10 AM ET TEMPS ALREADY IN THE LOWER 80S SOUTHWEST
OF THE FRONT. 2 AREAS OF MINOR INTEREST ARE 1) PATCH OF LOW
CLOUDS MOVING EAST INTO OUR WESTERN COUNTIES AND 2) SOUTHWARD
MOVING FEATURE (GRAVITY WAVE OR ELEVATED OUTFLOW) FROM THE
CONVECTION ACROSS NORTHERN MI. 12Z RAOBS SHOWING A VERY STRONG
CAP IN PLACE BEHIND THE WARM FRONT WITH ILX SHOWING +15 C AT
700 MB, DTX +11 AND ILN +13. TYPICALLY ANYTHING ABOVE 12 C IS
SUFFICIENT TO LIMIT UPDRAFTS IN CU. WITH REGARDS TO TEMPS AND
THE ABOVE NOTED FEATURES, THERE COULD BE SOME BRIEF SLOWDOWNS IN
THE RISING OF TEMPERATURES. HOWEVER, THE STRONG JUNE SUN WILL
QUICKLY CATCH UP IN THEIR WAKE SO FORECASTED HIGHS AND HEAT
INDICIES REMAIN ON TRACK.
DISCUSSION
ISSUED AT 208 AM EDT MON JUN 29 2026
AN ISOLATED AREA OF SHOWERS PERSISTS EARLY THIS MORNING ASSOCIATED
WITH UPSTREAM CONVECTION EARLIER IN THE DAY, EMBEDDED WITHIN AN
UPPER-LEVEL DISTURBANCE NOW SPILLING OVER THE EASTERN GREAT LAKES.
DESPITE AN OVERALL ABSENCE OF MEANINGFUL UPPER-LEVEL SUPPORT, THIS
ACTIVITY HAS SURVIVED WITHIN A NARROW CORRIDOR OF 500 J/KG OF MUCAPE
AND MID-LEVEL LAPSE RATES NEAR 7.5 C/KM.
AN EXTREME HEAT WARNING REMAINS IN EFFECT THROUGH THURSDAY AS A 594
DM RIDGE BUILDS OVER THE AREA. DAILY HIGHS IN THE 90S WITH AFTERNOON
HEAT INDICIES OF 100-105 CAN TAKE ITS TOLL. AS MENTIONED IN THIS
SPACE, HEAT HEADLINES MAY NEED TO CARRY ON INTO FRIDAY BUT THE
POSSIBILITY OF SHOWERS AND STORMS DIMINISHES CONFIDENCE SOMEWHAT.
DURING THIS STRETCH OF HEAT, THE NAEFS DEPICTS 99TH PERCENTILE
TEMPERATURES AND UPPER-LEVEL HEIGHTS RELATIVE TO 1979-2009
CLIMATOLOGY. THIS HIGHLIGHTS THE MAGNITUDE OF THIS BOUT OF HEAT.
PRECIPITABLE WATER VALUES ARE IN THE 90TH PERCENTILE, MARKING AN
UNSEASONABLY HUMID AIR MASS.
HIGH TEMPERATURES ARE LIKELY SAFE THIS WEEK, WITH RECORDS OF 98 TO
101 NOTED AT FORT WAYNE AND SOUTH BEND. HOWEVER, "WARM" LOW
TEMPERATURE RECORDS MAY BE SET, WITH RECORDS CURRENTLY IN THE MID-
70S.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 112 PM EDT MON JUN 29 2026
VFR CONDITIONS EXPECTED THROUGH THIS TAF PERIOD. SOME HAZE/MIST
CERTAINLY WOULD BE POSSIBLE OVER THE NEXT SEVERAL DAYS BUT AT
THIS TIME CONFIDENCE IS LOW AND HAVE LEFT ANY MENTION IN THE
OVERNIGHT HOURS EVEN WITH THE SMALL DEWPOINT DEPRESSIONS. ALSO,
A FEW TO SCATTERED FLAT CUMULUS MAY BE POSSIBLE WITH THE
DAYTIME HEATING/SURFACE INSTABILITY BUT LIKELY AROUND 5000 FT
AND AGAIN NOT HIGH CONFIDENCE AT THIS TIME. SOUTHWESTERLY WINDS
WILL BECOME BREEZY BY TUESDAY AFTERNOON WITH THE DIURNAL HEATING
AND GUSTS UP TO 20 KTS EXPECTED.
IWX WATCHES/WARNINGS/ADVISORIES
IN...EXTREME HEAT WARNING UNTIL 8 PM EDT /7 PM CDT/ THURSDAY FOR
INZ005>009-012>015-017-018-020-022>027-032>034-103-104-
116-203-204-216.
OH...EXTREME HEAT WARNING UNTIL 8 PM EDT THURSDAY FOR OHZ001-002-
004-005-015-016-024-025.
MI...EXTREME HEAT WARNING UNTIL 8 PM EDT THURSDAY FOR MIZ078>081-
177-277.
MARINE...NONE.
UPDATE...FISHER
DISCUSSION...BROWN
AVIATION...ANDERSEN
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