429
FXUS63 KIWX 180602
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
202 AM EDT Mon Aug 18 2025

.KEY MESSAGES...

- Mainly dry tonight and Monday, with the next notable chance
  of showers and thunderstorms (40-50%) late Monday night into
  Tuesday.

- Remaining hot and humid through the middle of the week.

&&

.DISCUSSION...
Issued at 227 PM EDT Sun Aug 17 2025

The stable layer left behind from morning`s shower and thunderstorms
has thus far fended off any redevelopment. A weak stationary front
is located along US 30 corridor and has been home to fair weather
cumulus bubbling up this afternoon as surface capping erodes. Aside
from this front, very little forcing to speak of for the remainder
of the afternoon. As a result, will carry a dry forecast through
much of Monday.

A low currently of the eastern Dakotas tracks east and arrives to
Lake Michigan Monday afternoon. Showers and thunderstorms may be
ongoing in the morning across WI and IL in the morning, but our well-
talked about ridge will remain in play. The surface low tracks well
north of our area leaving the surface fronts and the upper-level low
as our main forcing mechanism for any thunderstorms. The warm front
lifts in early Monday morning while the cold front moves through
Tuesday night. Mesoscale factors may throw wrenches at the overall
coverage of showers/storms. Thus, I didn`t too cute with POPs during
that timeframe. Look for increasing chances of showers and storms
Monday night through at least Tuesday morning. With respect to any
severe weather risk, shear continues to be a limiting factor while
instability appears greatest over IL (Monday evening) and far
northwest IN (Tuesday afternoon).

A cooler and less humid air mass settles in starting Wednesday with
high pressure taking shape over the Great Lakes. Some spurious POPs
linger from the in-house blend Wednesday, but high pressure ought to
suppress that 20% chance. A reinforcing dose of cooler air is still
in the cards for this weekend, preceded by another cold front with
showers and thunderstorms.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 149 AM EDT Mon Aug 18 2025

VFR to MVFR conditions at the TAF sites tonight. Over the past
few hours a patch of lower ceilings between 1500-2500 ft
developed just north and south of KFWA, with KFWA reporting
SCT023 as of this writing. The guidance largely has broken
ceilings between 5-10k, but doesn`t seem to be capturing the
recent development. Have a tempo for BKN025 at KFWA between
8-12z for now, but it`s possible we drop to 1500-2000ft if
development continues. Light easterly winds at both terminals
will gradually shift further southeastward through the period.

Predominantly VFR ceilings and dry conditions tonight into
Monday at KSBN. Some of the guidance produces light showers
between 15-19z either from a weak shortwave and/or outflow
boundary from upstream storms that should diminish west near
Chicago/Gary. Confidence is low, however if rain showers do
develop-we could see a brief period of 2500ft ceilings. It`s
also possible that the lower ceilings developing near KFWA
advect westward with easterly flow at the surface-but confidence
was too low to include a tempo. Used a prob30 for now.

&&

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

&&

$$

DISCUSSION...Brown
AVIATION...MCD