500
FXUS63 KIWX 101033
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
633 AM EDT Thu Jul 10 2025

.KEY MESSAGES...

- Strongest storms Friday afternoon and evening when SPC has a
  marginal severe storm risk.

- More storms are possible Saturday afternoon and evening. These
  storms are not expected to become severe.

- Very warm afternoon highs near 90 Friday and Saturday with
  heat indices in the 90s.

- There is a Moderate Swim Risk for southeast Lake Michigan
  beaches this morning.

&&

.DISCUSSION...
Issued at 258 AM EDT Thu Jul 10 2025

Patchy ground fog had developed overnight mainly over northeast
Indiana. Visibilities were extremely variable with the lowest
values at this time at GWB (1/2SM FG). A weak cold front had
moved southeast and had become quite diffuse from about TOL to
GGP. The front should wash out after daybreak with warm
temperatures this afternoon. An isolated storm is possible,
mainly in the favored convective time of 19Z to 01Z. Much better
chances for storms are ahead Friday and Saturday. Thunderstorms
are likely to fire on the weak front and also on old outflow
boundaries that have made it into the area on Friday. The
environment will become very unstable Friday afternoon with
basically a low shear/high CAPE setting. GFS CAPES reach as high
as 3500 J/Kg. Locally heavy rains and strong gusty winds are
possible. Precipitable water values will be hovering close to
anomalously high values of 2.0 inches. Strong storms are
possible again Saturday, depending how unstable conditions can
become and where boundaries are located. Otherwise, very warm
and humid conditions will develop during the afternoons of today
through Saturday. Heat indices are expected to rise will into
the 90s Friday and close to 100F Saturday afternoon.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 627 AM EDT Thu Jul 10 2025

Patchy fog continues this morning, with zone of greatest fog
just in the wake of weak surface cool front. Weak near sfc dry
air advection has resulted in a more limited fog threat across
far northwest Indiana. Still some potential for next hour or two
for KSBN to have some vsby restriction, but greatest potential
through 13Z for IFR conditions in fog should persist at KFWA.
Upstream Great Lakes low level anticyclone will provide weak
northwest winds of 5 to 10 knots today, and perhaps a little
stronger at KSBN this afternoon where some marine enhancement of
low level anticyclone could aid northerlies.

Attention for late this afternoon into tonight will be on
remnants of what should be MCV feature emanating from Upper
Midwest convection this morning. This convectively enhanced
disturbance will have limited downstream instability profiles to
work with initially later today, with low chances of showers
and thunderstorms expected later this evening and especially
overnight across NW Indiana as some modest low level return
theta-e advection works across the area. With uncertainty as to
how upstream forcing will evolve and likely limited instability,
will omit mention from TAFs at this time.

&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...Marsili