843
FXUS63 KIWX 290557
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
157 AM EDT Sat Aug 29 2026

.KEY MESSAGES...

- Mainly dry and trending warmer this weekend.

- Heat and humidity increases into next week with afternoon heat
  indices expected to reach well into the 90s for many.

- A primarily dry pattern should continue into at least the first
  half of next week.

&&

.DISCUSSION...
Issued at 120 PM EDT Fri Aug 28 2026

Quiet, pleasant weather will persist into this weekend as high
pressure shifts off to the east and the mid level flow becomes
increasingly zonal with little in the way of low level moisture
advection or forcing. Low level flow will turn more to the south-
southwest in this regime over the weekend allowing for a gradual
warming trend. Several weak perturbations in the height field
likely track east into the Great Lakes, one late tonight, and
then another Saturday afternoon into Saturday night. Convection
on the nose of a LLJ and developing MUCAPE axis likely remains
to the northwest of the area with the main impact locally being
an increase in mid-high level clouds with each passing wave.
With that said, cannot rule out decaying elevated showers
surviving into northern zones at some point Saturday night or
Sunday morning.

Building heat and humidity then becomes the story next week, at
least Monday through Wednesday, as a ~595 dm upper ridge at 500 mb
flexes north into the Ohio Valley and southern Great Lakes. Current
projections are for afternoon heat indices to reach well into the
90s each day, especially across the southern half of the forecast
area where ridge topping convective cloud debris is less likely to
spill over. Warm mid level profiles should put a lid on any surface
based convection for the bulk of these periods, though cannot rule
out convective outflow or elevated convection north of the US 30
corridor, especially toward the middle of the week. Models then
diverge for the second half of the week on whether the ridging
breaks down enough to send a frontal boundary either into or
through the area with low chances (20-30%) for showers/storms
and slightly cooler temps.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 155 AM EDT Sat Aug 29 2026

VFR conditions are expected this period. Some patchy shallow fog
is possible again this morning, but expecting these impacts to
be mainly for outlying areas and not direct impacts to
KFWA/KSBN. Northern Indiana remains on western periphery of an
expansive low level anticyclone with weak southeast flow less
than 5 knots overnight, becoming south 5 to 10 knots during the
day today. Ongoing convection across eastern SD this morning
will likely augment a mid/upper level trough which will work
into the southern Great Lakes region this evening. Isentropic
ascent and return of low/mid level moisture could yield some
weak elevated instability for some showers to develop across far
northern Indiana tonight. Given highly elevated nature to this
instability, confidence remains too low to include any precip
mention at the terminals at this time.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...Marsili