554
FXUS63 KIWX 240956
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
556 AM EDT TUE JUN 24 2025
KEY MESSAGES
- AN EXTREME HEAT WARNING CONTINUES IN EFFECT THROUGH THROUGH
THIS EVENING FOR WIDESPREAD HEAT INDICES AROUND 100 TO
LOCALLY 105 DEGREES.
- CUMULATIVE EFFECTS OF LONG-DURATION HEAT WILL LIKELY CAUSE
SIGNIFICANT IMPACTS AT LEAST THROUGH FRIDAY, ESPECIALLY WITH
VULNERABLE POPULATIONS.
- MILD OVERNIGHT LOWS IN THE 70S WILL EXACERBATE THE HEAT WAVE.
- THUNDERSTORMS WILL BECOME NUMEROUS MOST AFTERNOONS AND
EVENINGS THROUGH FRIDAY. STORMS MAY BECOME MARGINALLY SEVERE
TODAY AND WEDNESDAY WITH DAMAGING WINDS WILL BE THE MAIN HAZARD.
DISCUSSION
ISSUED AT 218 AM EDT TUE JUN 24 2025
THE HEAT WAVE WILL PERSIST TODAY FOR THE FOURTH DAY WITH AFTERNOON
HIGHS IN THE LOW TO MID 90S AND HEAT INDICES AROUND 100 TO LOCALLY
105 DEGREES. THEREFORE, HAVE KEPT THE EXCESSIVE HEAT WARNING IN
EFFECT TODAY. RESEARCH HAS SHOWN THESE HOT CONDITIONS ARE ESPECIALLY
BRUTAL ON THE MORE VULNERABLE POPULATIONS WHERE THE HEAT HAS
SIGNIFICANT IMPACTS WITH MULTIPLE HOT DAYS IN A ROW. HIGHS ARE
FORECAST TO BE IN THE UPPER 80S TO AROUND 90 THROUGH SUNDAY WHICH,
IF ALL OF THESE HOT DAYS ARE CONSIDERED, WOULD BRING THE HEAT
WAVE TO 8 DAYS (JUNE 21-28).
IN ADDITION TO THE HEAT, THUNDERSTORMS WILL ENTER THE FORECAST
TODAY. THE STORMS WILL BE MOST NUMEROUS DURING AFTERNOON AND
EVENINGS THROUGH FRIDAY. INTENSE HEATING TODAY AND WEDNESDAY MAY
BRING SOME STORMS TO THE THRESHOLD OF BECOMING SEVERE. ALTHOUGH
WIND FLOW AND WIND SHEAR WILL BE GENERALLY WEAK, AFTERNOON
INSTABILITY MAY TOP 3000 J/KG PER NAM BUFKIT CAPE FAVORING A
HIGH CORRELATION WITH A DIURNAL WINDOW OF 19Z TO 01Z. THERE IS
A SIGNAL FOR HEAVY PRECIPITATION GIVEN THE LIKELY SLOW STORM
MOVEMENT AND ANOMALOUSLY HIGH PRECIPITABLE WATER VALUES NEAR 1.8
INCHES WHICH IS ABOVE THE 95TH PERCENTILE FOR THE FORECAST AREA
FOR THIS TIME OF YEAR.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 121 AM EDT TUE JUN 24 2025
AN OUTFLOW BOUNDARY FROM A DECAYING LINE OF SHOWERS AND
THUNDERSTORMS IS APPROACHING KORD, TRACKING SOUTHEAST. THIS
FEATURE APPEARS TO BE WEAKENING. THIS IN-HOUSE TIME OF ARRIVAL
TOOL SUGGESTED AN ARRIVAL TIME TO KSBN NEAR 09Z; THUS FORWARD
PROGRESS IS SLOW. SEEING THE DECAYING TREND ON RADAR RETURNS, I
WILL OMIT AN OUTFLOW WINDSHIFT TO THE NORTHWEST BUT WILL
CONTINUE TO MONITOR.
A SOMEWHAT MURKY TAF PERIOD AHEAD WITH SCATTERED THUNDERSTORMS
ANTICIPATED THIS AFTERNOON. I DID ADJUST THE TIMING A TOUCH
BASED ON THE LATEST MODEL TRENDS. LATE IN THE PERIOD,
ADDITIONAL SHOWERS AND STORMS APPROACH KSBN (LOW CONFIDENCE)
WHILE THIS ACTIVITY PERHAPS ARRIVES AT KFWA JUST OUTSIDE THIS
TAF PERIOD.
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...SKIPPER
AVIATION...BROWN
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