452
FXUS63 KIWX 020542
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
142 AM EDT THU JUL 2 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 /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 140 AM EDT THU JUL 2 2026
WIDESPREAD SHOWERS AND STORMS CONTINUE EARLY THIS MORNING ALONG
AN AXIS FROM SOUTHEAST MINNESOTA TO THE NORTHERN LAKE MICHIGAN
VICINITY. MID LEVEL RIDGING ACROSS THE OHIO VALLEY SHOULD HOLD
ENOUGH STRENGTH THIS MORNING TO KEEP FOCUS FOR SHOWERS AND
STORMS WELL NORTHWEST OF THE TERMINALS. HOWEVER, MAY NEED TO
WATCH PROGRESS OF SOUTHEAST PROGRESSING OUTFLOW BOUNDARY FROM
THIS CONVECTION, AND IF CAN REACH AS FAR SOUTH AS THE SOUTHERN
GREAT LAKES. THIS OUTFLOW COULD KICK OFF AN ISOLATED SHOWER OR
STORM DURING THE DAY TODAY, BUT CONFIDENCE IN OCCURRENCE AND
LIMITED COVERAGE STILL SUGGESTS OMITTING MENTION FROM TAFS IS
BEST COURSE OF ACTION AT THIS TIME. CHANCES OF SHOWERS AND
STORMS MAY TEND TO INCREASE LATE IN THIS FORECAST VALID PERIOD
THIS EVENING AS MID LEVEL RIDGE BECOMES SLIGHTLY MORE SUPPRESSED
AND AS ANOTHER CONVECTIVELY ENHANCED IMPULSE TOPS THE RIDGE
ACROSS THE CORN BELT. OTHERWISE, CANNOT COMPLETELY RULE OUT SOME
BRIEF MVFR VSBYS IN LIGHT SHALLOW FOG EARLY THIS MORNING, BUT
VFR CONDITIONS SHOULD HOLD THROUGH THE PERIOD. IN SIMILAR
FASHION TO YESTERDAY, PEAK MIXING THIS AFTERNOON SHOULD YIELD
SOUTHWEST WINDS AROUND 20 KNOTS AT KSBN WHERE GRADIENT SHOULD BE
A BIT MORE PRONOUNCED.
IWX WATCHES/WARNINGS/ADVISORIES
IN...EXTREME HEAT WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING
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 THIS EVENING FOR OHZ001-
002-004-005-015-016-024-025.
MI...EXTREME HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR
MIZ078>081-177-277.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...MARSILI
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