025
FXUS63 KIWX 301025
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
625 AM EDT TUE JUN 30 2026
KEY MESSAGES
- EXTREME HEAT WARNING IS IN EFFECT THROUGH THURSDAY EVENING.
DAILY HIGHS IN THE 90S AND HEAT INDICES GREATER THAN 100
DEGREES. LOWS IN THE MID-70S PROVIDE MINIMAL RELIEF.
- REMAINING HOT ON FRIDAY WITH INCREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS.
DISCUSSION
ISSUED AT 228 AM EDT TUE JUN 30 2026
WATER VAPOR IMAGERY EARLY THIS MORNING DEPICTS A TOWERING RIDGE OVER
THE EASTERN-HALF OF THE CONUS, WITH A 1019MB SURFACE HIGH ANALYZED
OVER ALABAMA. CONVECTION OVER THE UPPER GREAT LAKES MAY ALLOW SOME
DEBRIS CLOUDS OVERHEAD THIS MORNING, BUT THIS WILL HAVE LIMITED
IMPACTS TO TODAY'S HEAT AND HUMIDITY.
OUR UPPER-LEVEL RIDGE AMPLIFIES SOMEWHAT TODAY AND SHIFTS A TOUCH
NORTH AS WELL. THIS, ALONG WITH EARLY-MORNING TEMPERATURES WILL INTO
THE 70S THIS HOUR, WILL PROPEL TEMPERATURES A FEW DEGREES WARMER
THAN MONDAY. HEAT INDEX VALUES OF 100-108 WERE REALIZED MONDAY AND
WE EXPECT MORE OF THE SAME THIS AFTERNOON. THE EXTREME HEAT WARNING
CARRIES ON THROUGH THURSDAY, AND NEIGHBORING OFFICES HAVE UPGRADED
HEADLINES TO JOIN THE WARNING.
MODEL GUIDANCE CONTINUES TO SHOW HINTS THAT THIS RIDGE WILL EASE
SOMEWHAT ON FRIDAY AS THE 500-MB PATTERN IN THE WEST FLATTENS,
ALLOWING DOWNSTREAM FLOW TO FLATTEN ATOP THE NOW-DISPLACED RIDGE.
THIS CHANGE PERMITS SHOWERS AND THUNDERSTORMS TO ENTER THE LATE-WEEK
FORECAST, BUT SPECIFICS ARE SPARSE IN WHAT WILL BE A DAY-TO-DAY
CONVECTIVE ENVIRONMENT. LOOKING SEASONABLY WARM EARLY NEXT WEEK,
WITH HIGHS WELL INTO THE 80S.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 620 AM EDT TUE JUN 30 2026
A UNIQUE FEATURE ON WATER VAPOR AND SATELLITE IMAGERY HAS
RESULTED IN A NARROW AREA OF STRATUS OVER NORTHERN INDIANA. AN
OUTFLOW BOUNDARY (OR OTHER CONVECTIVE FEATURE) APPEARS TO HAVE
SPILLED INLAND FROM A DECAYING COMPLEX OF STORMS EAST OF
TORONTO, ON. A FURTHER MARINE-LAYER INFLUENCE OFF HURON AND ERIE
COULD BE AT PLAY AS WELL. ANYWAY, WITH DAYTIME MIXING UNDERWAY
SHORTLY, THIS STRATUS OUGHT TO BE SHORT LIVED. I'LL MAINTAIN A
VFR TAF AT KSBN AS THEY APPEAR TO BE FURTHER REMOVED FROM THE
WESTWARD EXTEND OF THIS INTERESTING FEATURE. HIGHER CONFIDENCE
AT KFWA YIELDS A TEMPO.
OTHERWISE, DIURNAL TREND WITH SW WIND TODAY, INCLUDING A FEW
GUSTS NEAR 20 KNOTS.
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.
AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MIZ177-277.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...BROWN
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