948
FXUS63 KLOT 062314
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
614 PM CDT Sat Sep 6 2025

.KEY MESSAGES...

- Unseasonably cool conditions through Monday morning.

- Low chances (20%-30%) for showers midweek.

&&

.DISCUSSION...
Issued at 233 PM CDT Sat Sep 6 2025

One final disturbance rotating around the large upper low will
move southeast across the western Great Lakes region this
afternoon into this evening. The bulk of any precipitation with
this system is expected to remain north and northeast of the
local area, but a few showers may clip far northeast IL this
evening and have added some low chance pops for this potential.
Its possible if anything develops, it may remain sprinkles/
virga. Mostly cloudy skies this evening, especially along north
of I-80 will scatter out overnight with mainly clear skies
expected by morning. Gusty west/northwest winds will diminish
with sunset and likely be 5 mph or less by morning and combined
with the expected mainly clear skies, lows will be in the 40s
for most areas, with the usual cool spots possibly dipping into
the upper 30s.

High pressure will move across the area Sunday with light winds
allowing for a lake breeze to form. Still some uncertainty for
how far inland it may move, but with highs generally in the
mid/upper 60s inland, slightly cooler temps are possible near
Lake Michigan. Despite some weak warm air advection Sunday night
into Monday morning, clear skies and likely calm winds for most
locations may result in similar low temps Monday morning as
expected Sunday morning, with the usual cool spots possibly
dipping in the upper 30s again.

A weak upper trough is expected to move across the area Tuesday
night. Precip chances with this feature look rather small and
confidence is low. Blended pops have low chance pops across the
northern third or so of the cwa and that seems reasonable for
now. Depending on its eventual strength and speed, a few
showers may be possible Tuesday afternoon and also on Wednesday.

While temps will warm through midweek, models show a cold front
moving across the area Wednesday afternoon or Wednesday night.
This turns winds northeasterly and off Lake Michigan. With not
much change to thermal profiles, this may allow for highs in
the lower 80s well inland to mid/upper 70s closer to the lake
and perhaps only lower 70s right along the shore on Thursday
and Friday.

Quite a bit of uncertainty for late next week and especially
next weekend. While the overall trend looks warmer with perhaps
well above normal temps, the ensembles still have 20%-30% of
their members showing rather cool/below normal temps. And this
uncertainty seems apparent in the operational 12z runs of the
GFS/ECMWF, with the latter showing a strong cold front just
beyond the end of this 7 day period, and thus a possible cooler
pattern. cms

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 614 PM CDT Sat Sep 6 2025

While some intermittent gustiness may continue this evening,
persistent gusts are expected to ease, with W to NW winds around
10 knots prevailing. Can`t rule out a few sprinkles developing
during the 01-05z timeframe, but chances are too low for any
precip mention in the outgoing TAFs.

NW winds will pick up a bit through Sunday morning and
afternoon. Intermittent gusts around 15 kts will be possible. A
lake breeze will develop and appears likely to move through GYY
and MDW during the afternoon. Confidence in the E/ENE wind shift
making it to ORD remains around 30 percent at this time. If the
lake breeze does make it to ORD, this likely wouldn`t be until
after 22-23z, with the lake breeze in a weakening state. VFR
conditions are expected through the TAF period.

Carlaw

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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