629
FXUS63 KIWX 011734
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
134 PM EDT WED JUL 1 2026
KEY MESSAGES
- THE EXTREME HEAT WARNING REMAINS IN EFFECT AREA-WIDE THROUGH THURSDAY
EVENING. HIGHS IN THE LOW TO MID 90S AND HEAT INDICES BETWEEN
100 TO 110 DEGREES ARE EXPECTED THIS AFTERNOON AND AGAIN
THURSDAY.
- NEAR RECORD WARM OVERNIGHT LOWS IN THE MID 70S WILL OFFER LITTLE
TO NO RELIEF AT NIGHT.
- HEAT INDICES MAY EXCEED 100 DEGREES AGAIN ON FRIDAY, BUT HEAT INDICES
WILL BE DEPENDENT ON EXTENT OF AFTERNOON CLOUDS AND ANY
SCATTERED SHOWERS AND STORMS.
- HIGHS IN THE UPPER 80S TO LOW 90S FOR THE 4TH OF JULY WITH UP
TO 60% CHANCES FOR SCATTERED RAIN AND STORMS IN THE AFTERNOON
AND EVENING.
DISCUSSION
ISSUED AT 130 PM EDT WED JUL 1 2026
A STRONG UPPER LEVEL RIDGE CONTINUES TO BRING VERY HOT AND
HUMID CONDITIONS THROUGH AT LEAST THURSDAY, POSSIBLY FRIDAY. AS
SURFACE HIGH PRESSURE STRENGTHENS OVER THE SOUTHEAST US,
SOUTHWEST FLOW INTO OUR AREA CONTINUES TO USHER IN VERY HUMID
AIR WITH DEWPOINTS IN THE MID 70S CURRENTLY. SURFACE
OBSERVATIONS SHOW TEMPERATURES IN THE UPPER 80S TO LOW 90S NOW,
WITH TEMPERATURES LIKELY CLIMBING A FEW DEGREES HIGHER THIS
AFTERNOON FOR HIGHS UNDER MOSTLY SUNNY SKIES. THE EXTREME HEAT
WARNING REMAINS IN EFFECT AREA-WIDE THROUGH SUNSET TOMORROW.
DAYTIME HIGHS ARE EXPECTED TO REACH THE LOW TO MID 90S THIS
AFTERNOON AND AGAIN THURSDAY WITH PEAK AFTERNOON HEAT INDICES
BETWEEN 100 TO 110 DEGREES BOTH DAYS. NEAR RECORD WARM LOWS IN
THE MID 70S OVER THE NEXT FEW NIGHTS WILL OFFER VERY LITTLE TO
NO REPRIEVE FROM THE HEAT. DUE TO THE DURATION AND INTENSITY OF
THE HEATWAVE, HEATRISK WILL BE MAXED OUT AT MAJOR TO EXTREME
ACROSS THE AREA TODAY AND AGAIN ON THURSDAY, MEANING THE HEAT
CAN IMPACT ANYONE REGARDLESS OF ADEQUATE COOLING OR HYDRATION.
OUR FORECAST CURRENTLY STILL HAS PEAK HEAT INDICES ABOVE 100
DEGREES AGAIN ON FRIDAY, ESPECIALLY ALONG AND EAST OF I-69.
THERE WAS COLLABORATION TODAY WITH NEIGHBORING OFFICES AS TO
WHETHER OR NOT THE EXTREME HEAT WARNING SHOULD BE EXTENDED
THROUGH FRIDAY. THE DECISION WAS MADE FOR OUR AREA TO WAIT ON A
DECISION DUE TO POTENTIAL FOR RAIN/STORMS ON FRIDAY. LINGERING
CLOUD COVER AND ANY RAIN/STORMS IN THE AREA MAY LIMIT PEAK HEAT
INDICES BELOW CRITERIA. THERE MAY END UP BEING A SCENARIO WHERE
THE EASTERN PART OF THE AREA HAS THE EXTREME HEAT WARNING
EXTENDED FOR FRIDAY AND THE WESTERN HALF HAS A HEAT ADVISORY.
AS THE UPPER LEVEL RIDGE FLATTENS AND BEGINS TO BREAK DOWN ON FRIDAY
AND INTO THE WEEKEND, RAIN/STORM CHANCES RETURN TO OUR AREA JUST IN
TIME FOR THE 4TH OF JULY WEEKEND. EXACT DETAILS ARE UNCERTAIN AND
CONFIDENCE IS VERY LOW IN EXACT TIMING/PLACEMENT OF RAIN/STORMS, BUT
WE WILL HAVE TO MONITOR FOR COMPLEXES OF STORMS (MCSS) THAT RIDE THE
PERIPHERY OF THE FLATTENING RIDGE. MODEL GUIDANCE IS SPLIT BUT
CHANCES FOR RAIN/STORMS COULD RETURN AS EARLY AS FRIDAY MORNING
DEPENDING ON UPSTREAM CONVECTION. SOME MODELS (ESPECIALLY THE ECMWF
AND GEM) HINT AT A DECAYING MCS MOVING IN FROM ILLINOIS FRIDAY
MORNING/AFTERNOON. HOWEVER, NBM PROBABILITIES ONLY HAVE ABOUT 40-50%
CHANCES FOR MEASURABLE RAINFALL (0.01") IN ANY 6 HR PERIOD ON
FRIDAY. BETTER CONFIDENCE IN CONVECTION ARRIVES BY THE HOLIDAY
WEEKEND SINCE WE WILL FINALLY HAVE A STATIONARY FRONT IN THE
VICINITY TO PROVIDE A SOURCE OF LIFT FOR STORMS. AS OF RIGHT NOW, IT
DOES NOT APPEAR LIKE JULY 4TH WILL BE A COMPLETE WASHOUT. HOWEVER,
PRECIPITATION CHANCES WILL LIKELY BE DIURNAL, FAVORING THE AFTERNOON
AND EVENING TIMEFRAME FOR THE HIGHEST POPS OF UP TO 60% ON JULY 4TH.
SCATTERED SHOWERS AND STORMS ARE POSSIBLE ON THE 4TH OF JULY WITH
HIGHS IN THE UPPER 80S TO LOW 90S. WHILE IT MAY BE SLIGHTLY 'COOLER'
INTO EARLY NEXT WEEK WITH HIGHS IN THE 80S, THE LONG TERM PATTERN
CONTINUES TO FAVOR ABOVE NORMAL TEMPERATURES THROUGH MID JULY.
PERIODIC CHANCES FOR RAIN/STORMS NEXT WEEK AS ZONAL FLOW ALOFT
CONTINUES.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 134 PM EDT WED JUL 1 2026
THE MAIN WEATHER PHENOMENON IN CONTROL OF OUR LOCAL WEATHER IS THE
STRONG RIDGE ACROSS THE SOUTHEASTERN US. SHORTWAVES ATTEMPT TO
BUCKLE IT OVER THE NEXT COUPLE OF DAYS, BUT IT APPEARS TO HOLD STOUT
IN THE SHORT TERM, KEEPING THUNDERSTORM ACTIVITY TO THE NORTH TODAY
AND TONIGHT. AS SUCH, VFR CONDITIONS LOOK TO CONTINUE. THE ONE
FLY IN THE OINTMENT MIGHT BE THE HAZE/LOW FOG POSSIBILITY
RETURNING AGAIN THU AM. AFTERNOON MIXING TODAY INTO THE LLJ
ALLOWS FOR 20 TO 25 KT MORE FREQUENTLY AT SBN, BUT ALSO POSSIBLY
AT FWA. WINDS STAY GENERALLY OUT OF THE SOUTHWEST THROUGH THE
PERIOD.
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.
DISCUSSION...JOHNSON
AVIATION...ROLLER
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