433
FXUS63 KIWX 090806
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
406 AM EDT Wed Jul 9 2025

.KEY MESSAGES...

- Becoming hot and humid Friday and Saturday. Highs in the upper 80s
with heat indices in the low to mid 90s.

- Chances abound for mainly afternoon and evening showers and
  thunderstorms through early next week.

- Severe storms are not expected.


&&

.DISCUSSION...
Issued at 258 AM EDT Wed Jul 9 2025

Incredibly stable mid level (700mb-500mb) lapse rates in the
order of 4.7 to 5.0 C/Kg were over northern Indiana and
surrounding areas. Scattered showers and a few storms have
survived the night in the base of the upper level trof that was
moving through the Upper Great Lakes region. Scattered showers
and storms will become more numerous by late this afternoon with
daytime heating. Severe storms are not expected, but locally
heavy rainfall and wind gusts up to 40 mph will be possible.
There should be a short break in the activity Thursday with
somewhat more stable air, slightly lower dew points and weak
subsidence.

An upper level trof topping the subtropical ridge extension was
over the southwest CONUS will phase with another wave moving
east across southern Canada. These merging systems will bring a
good chance for showers and storms Friday. Given the stable
conditions, heavy rainfall is not expected. After Friday,
numerous chances for showers and storms will persist through the
middle of next week given the environment of high precipitable
water values and deep moisture.


&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 145 AM EDT Wed Jul 9 2025

A convectively enhanced short wave will continue to track across
northern Indiana this morning with some scattered showers and
isolated thunderstorms. Instability is a limiting factor
however, with CIN for near sfc based parcels persisting.
Confidence at this time is too low for inclusion of showers at
terminals overnight, but trends will continue to be monitored
through the daybreak. The best chance may be at KSBN where
remnant MCV feature across NE Illinois could speak some early
morning showers/isolated storms. Broad upstream upper trough
will take a baggy sfc trough/cool front into northern Indiana
today with a diurnal uptick in showers and embedded storms
expected. This potential appears to affect both terminals and
will continue idea from previous forecast in PROB30 mention
through mid/late afternoon at KSBN, and mid afternoon through
early evening at KFWA based on frontal timing. Drier low level
air will eventually seep into northern Indiana tonight behind
this front. This setup could yield some patchy shallow fog
development across NE Indiana early Thursday morning but this
will be addressed in next TAF issuance.

&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...Marsili