695
FXUS63 KIWX 232245
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
645 PM EDT MON JUN 23 2025
KEY MESSAGES
- AN EXTREME HEAT WARNING REMAINS IN EFFECT THROUGH TUESDAY
EVENING. PEAK HEAT INDICES OF 100 TO 105 DEGREES ARE EXPECTED
TODAY AND TOMORROW.
- CUMULATIVE EFFECTS OF LONG-DURATION HEAT WILL LIKELY CAUSE
SIGNIFICANT IMPACTS AT LEAST THROUGH MIDWEEK.
- NEAR RECORD WARM OVERNIGHT LOW TEMPERATURES IN THE LOW TO MID
70S WILL PROVIDE LITTLE TO NO RELIEF FROM THE HEAT,
ESPECIALLY FOR VULNERABLE POPULATIONS.
- BEST CHANCES FOR RAIN AND STORMS THIS WEEK WILL BE WEDNESDAY AFTERNOON
AND EVENING, ALTHOUGH DAILY CHANCES WILL EXIST BETWEEN
TUESDAY THROUGH FRIDAY. THERE IS A MARGINAL RISK FOR ISOLATED
STRONG TO SEVERE STORMS TUESDAY AFTERNOON AND EVENING, AND
THEN AGAIN ON WEDNESDAY. DAMAGING WIND WILL BE THE PRIMARY
HAZARD.
DISCUSSION
ISSUED AT 241 PM EDT MON JUN 23 2025
AN AREA OF SURFACE HIGH PRESSURE AND AN EXPANSIVE UPPER LEVEL
RIDGE WILL CONTINUE BRING HIGH HEAT AND OPPRESSIVE HUMIDITY TO
THE AREA THIS WEEK. THE EXCESSIVE HEAT WARNING REMAINS IN EFFECT
THROUGH 8 PM ET TUESDAY. AMPLE WAA AND MOISTURE TRANSPORT FROM
THE GULF WILL YIELD HIGHS IN THE LOW TO MID 90S AND DEWPOINTS IN
THE MID 70S OVER THE NEXT SEVERAL DAYS. NEAR RECORD OVERNIGHT
LOWS IN THE MID 70S WILL OFFER LITTLE TO NO RELIEF FROM THE
HEAT, SO CUMULATIVE HEAT IMPACTS ARE LIKELY. PEAK HEAT INDICES
LATER TODAY AND TUESDAY AFTERNOON WILL BE BETWEEN 100 TO 105
DEGREES AREA-WIDE. THE NWS HEAT RISK SHOWS MAJOR TO EXTREME
(LEVELS 3 AND 4 OUT OF 4) HEAT IMPACTS WILL BE POSSIBLE FOR THE
REST OF TODAY THROUGH TUESDAY. STAY HYDRATED, TAKE BREAKS IF YOU
MUST BE OUTSIDE, AND CHECK IN ON THOSE WHO COULD BE ESPECIALLY
VULNERABLE TO THE HIGH HEAT AND HUMIDITY. ADDITIONAL HEAT
HEADLINES MAY BE NEEDED BEYOND TUESDAY GIVEN THAT HIGH
TEMPERATURES ARE STILL FORECAST TO BE IN THE UPPER 80S MID TO
LATE IN THE WEEK WITH HEAT INDICES PEAKING BETWEEN 95 TO 100
DEGREES, ESPECIALLY ALONG AND SOUTH OF US 30.
AS THE RIDGE FLATTENS OUT BY MIDWEEK AND CHANCES FOR RAIN/STORMS
RETURN, WE MAY GET SOME REPRIEVE FROM THE DANGEROUS HEAT. CONFIDENCE
IS LOW TO MEDIUM FOR THE HEAT CONTINUING PAST MIDWEEK, AS THE
TEMPERATURE FORECAST WILL BE HIGHLY DEPENDENT ON IF WE GET ANY
STORMS OR REMNANT OUTFLOW BOUNDARIES OVER THE AREA. DAILY DIURNAL
CHANCES FOR RAIN/STORMS EXIST THIS WEEK STARTING TUESDAY, HOWEVER,
THIS IS A TOUGH FORECAST PATTERN FOR MODELS TO RESOLVE. MODEL
GUIDANCE TYPICALLY STRUGGLES WITH A PATTERN LIKE THIS AS IT IS TOUGH
TO KNOW WHAT WILL OCCUR A FEW DAYS OUT WHEN THERE IS CONSIDERABLE
UNCERTAINTY AS TO IF AND WHEN STORMS DEVELOP. IF STORMS DO MANAGE TO
DEVELOP IN OUR AREA ON ANY GIVEN DAY, THIS COULD MEAN TEMPERATURES
END UP COOLER THAN ORIGINALLY FORECAST (ESPECIALLY IF ANY
OUTFLOW BOUNDARIES MOVE THROUGH). A COLD FRONT OVER THE MIDWEST
AND CENTRAL PLAINS WILL STALL OFF TO OUR WEST OVER THE NEXT
24-36 HOURS, FINALLY REACHING OUR FORECAST AREA BY WEDNESDAY. IT
IS POSSIBLE SOME REMNANT OUTFLOW BOUNDARIES ASSOCIATED WITH
THIS FRONT DRIFT EAST INTO OUR AREA ON TUESDAY, WHICH IS WHY WE
HAVE CHANCES FOR AFTERNOON/EVENING POP-UP SCATTERED SHOWERS AND
STORMS. WITH OUR AREA ON THE NORTHERN PERIPHERY OF THE RIDGE, IT
IS ALSO POSSIBLE WE GET SOME RAIN/STORMS IN OUR AREA MID TO
LATE IN THE WEEK AS THE RIDGE STARTS TO BREAK DOWN AND STORM
COMPLEXES RIDE THE FRINGES OF THE RIDGE. BEST CHANCES FOR
RAIN/STORMS THIS WEEK WILL LIKELY BE WEDNESDAY AFTERNOON/EVENING
AS THIS COLD FRONT MOVES THROUGH. THE PERSISTENT HIGH HEAT AND
HUMIDITY WILL MAKE FOR A VERY UNSTABLE AIRMASS. DEWPOINTS IN THE
LOW TO MID 70S EACH DAY AND TEMPERATURES IN THE LOW TO MID 90S
WILL CREATE ANYWHERE FROM 2500 TO 4000 J/KG OF SBCAPE ON TUESDAY
AND WEDNESDAY. WITH HOW MOIST AND UNSTABLE THE ATMOSPHERE
OVERHEAD IS, IT IS NOT UNREASONABLE TO THINK THAT STORMS COULD
DEVELOP AND BECOME STRONG TO SEVERE. THE STORM PREDICTION CENTER
CURRENTLY HAS US IN A MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE
WEATHER ON TUESDAY AND WEDNESDAY. THE MAIN HAZARD AT THIS TIME
WOULD BE DAMAGING WINDS.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 641 PM EDT MON JUN 23 2025
VFR CONDITIONS EXPECTED THROUGH AT LEAST 18Z TUE BEFORE CHANCES
INCREASE FOR SHOWERS/T-STORMS WHICH MAY SLIGHTLY LOWER VSBYS IN
RAIN. THERE IS A VERY LOW CHANCE OF A SHOWER OR THUNDERSTORM
POSSIBLE ESPECIALLY FOR KSBN AFTER 07Z TUE HOWEVER CONFIDENCE IS
LOW AND DID NOT PUT MENTION IN THE TAFS. LIGHT SOUTHWESTERLY
WINDS CONTINUE THROUGH TAF PERIOD, OUTSIDE OF ANY THUNDERSTORM
OUTFLOWS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...EXTREME HEAT WARNING UNTIL 8 PM EDT /7 PM CDT/ TUESDAY 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 TUESDAY FOR OHZ001-002-004-
005-015-016-024-025.
MI...EXTREME HEAT WARNING UNTIL 8 PM EDT TUESDAY FOR MIZ078>081-177-
277.
AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MIZ078-177-
277.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...ANDERSEN
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