394
FXUS63 KIWX 300437
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1237 AM EDT Tue Jun 30 2026

.KEY MESSAGES...

- Extreme Heat Warning is in effect through Thursday evening
  for an extended period of high heat indices and limited
  nighttime cooling.

- Heat may remain a concern Friday, but chances for showers and
  thunderstorms begin to increase resulting in lower confidence
  on the amount of impacts.

&&

.DISCUSSION...
Issued at 140 PM EDT Mon Jun 29 2026

Forecast generally on track with the main focus into Thursday
remaining on the extended period of heat and humidity. Dewpoints
continue to climb and are somewhat concerning as hints of some of
the model blends are appearing as pockets of 76 to 78 degree values
are being noted even back into IL. Always a fine balance on how warm
air temps can get as the very high dewpoints arrive, but low to mid
90s still seem reasonable over the next several days. A strong mid
level cap, depicted by 700 mb temps of +12 to +15 C, should keep any
convective chances nearly non existent through at least Wednesday.

Starting Thursday the upper level ridge begins to weak ever so
slightly and may allow for some widely scattered shower/storm
development mainly in the west or northwest. The ridge slowly gives
way over the weekend, especially Sunday into next week as it
flattens out somewhat. Chances for convection will generally be
diurnal, but will need to monitor for upstream complexes each day
and possible impacts. As for heat concerns, the warning continues
into Thursday with some potential for extension into Friday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1236 AM EDT Tue Jun 30 2026

Status quo for this round of TAFs. Upper-level ridge offers FEW
to SCT skies with a diurnal uptick in southwesterly flow.

&&

.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...Fisher
AVIATION...Brown