NWS Chicago Decision Support Briefing - Forecast

880
FXUS63 KLOT 011936
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
236 PM CDT Wed Oct 1 2025

.KEY MESSAGES...

- Dry and unseasonably warm daytime conditions to persist
through the weekend.

&&

.DISCUSSION...
Issued at 236 PM CDT Wed Oct 1 2025

A mid-level ridge continues to reside across the Great Lakes,
but the broad trough ejecting out of the central Plains is
starting to push the ridge further east. While this trough won`t
give us any rainfall, it will allow a broad cirrus shield to
mover the area resulting in partly clear skies for tonight into
Thursday morning. As a result temperatures this afternoon have
likely hit their peak and should remain in the upper 70s to
around 80 (low to mid-70s lakeside) before cooling into the low
to mid-50s overnight. With the cirrus shield expected to clear
from west to east Thursday afternoon, it looks as if highs
should be able to recover back into the mid to upper 80s.
Though, a weak lake breeze does look to keep temperatures cooler
along the IL shoreline where highs should remain in the mid-70s
once again.

Another mid-level ridge is expected to establish across the
southern CONUS and extend into the Great Lakes Friday through
the weekend. However, a long wave trough will be traversing
across the western CONUS at the same time with several
shortwaves forecast to eject into the northern Plains this
weekend. While these troughs are not forecast to do much for our
weather, they will set up a fairly tight pressure gradient
across the Midwest and Great Lakes, particularly in the mid and
upper levels, resulting in a period of breezy winds. Couple
these winds with the already dry and unseasonably warm
conditions (highs in the mid to upper 80s areawide each day)
will put some of the ingredients in place for a heightened fire
weather risk Saturday and especially on Sunday. Given that there
is some uncertainty as to how low dew points will get this
weekend, saw no need to deviate from the low to mid-50s dew
points advertised by the blended forecast. That said, if the
deeper mixed forecast solutions materialize then further
refinement may be needed.

Heading into next week, guidance continues to show a change to
our warm and dry pattern as the aforementioned trough pivots
into the Great Lakes and pushes a cold front into northern IL
and northwest IN. While there continues to be some uncertainty
as to the exact timing of the front`s arrival, the signal
remains fairly strong for a period of showers during the Monday
through Tuesday timeframe and thus the 20-30% POPs have been
maintained. In the wake of the front temperatures are forecast
to trend towards more seasonable readings with highs in 60s and
70s and overnight lows in the 40s and 50s.

Yack

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1203 PM CDT Wed Oct 1 2025

Expect VFR conditions with cirrus and perhaps a few diurnal
cumulus through Thursday. Winds will favor ENE/E around 10 knots
through this evening and ESE/SE under 10 knots overnight and
Thursday.

Kluber

&&

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

&&

$$

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