746 

FXUS63 KIWX 291026

AFDIWX



Area Forecast Discussion

National Weather Service Northern Indiana

626 AM EDT Mon Jun 29 2026



.KEY MESSAGES...



- Isolated showers and embedded thunderstorms toward the I-69 

  corridor early this morning. 



- 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 208 AM EDT Mon Jun 29 2026



An isolated area of showers persists early this morning associated 

with upstream convection earlier in the day, embedded within an 

upper-level disturbance now spilling over the eastern Great Lakes. 

Despite an overall absence of meaningful upper-level support, this 

activity has survived within a narrow corridor of 500 j/kg of MUCAPE 

and mid-level lapse rates near 7.5 C/km.



An Extreme Heat Warning remains in effect through Thursday as a 594 

dm ridge builds over the area. Daily highs in the 90s with afternoon 

heat indicies of 100-105 can take its toll. As mentioned in this 

space, heat headlines may need to carry on into Friday but the 

possibility of showers and storms diminishes confidence somewhat. 

During this stretch of heat, the NAEFS depicts 99th percentile 

temperatures and upper-level heights relative to 1979-2009 

climatology. This highlights the magnitude of this bout of heat. 

Precipitable water values are in the 90th percentile, marking an 

unseasonably humid air mass. 



High temperatures are likely safe this week, with records of 98 to 

101 noted at Fort Wayne and South Bend. However, "warm" low 

temperature records may be set, with records currently in the mid-

70s.



&&



.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...

Issued at 621 AM EDT Mon Jun 29 2026



Variable cloudiness this morning with debris clouds from earlier

showers and thunderstorms, and even from convection crossing far

northern Lake Michigan this hour. A warm front lifts north today

which should allow ceilings should SCT out. A few wind gust 

near 20 knots this afternoon with an increasing pressure 

gradient.



During this hot and humid stretch, cannot rule out patchy 

ground fog daily near sunrise. Time height cross sections 

depict low- level moisture pooling beneath a weak inversion, but

wind Tuesday morning above 5 knots may keep any BR at bay. 



&&



.IWX WATCHES/WARNINGS/ADVISORIES...

IN...Extreme Heat Warning from 2 PM EDT /1 PM CDT/ this afternoon 

     to 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 from 2 PM this afternoon to 8 PM EDT 

     Thursday for OHZ001-002-004-005-015-016-024-025.

MI...Extreme Heat Warning from 2 PM this afternoon to 8 PM EDT 

     Thursday for MIZ078>081-177-277.

MARINE...None.



&&



$$



DISCUSSION...Brown

AVIATION...Brown