624
FXUS63 KLOT 262056
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
256 PM CST Wed Nov 26 2025

.KEY MESSAGES...

- Strong westerly winds (gusts of 45 to 50 mph), much colder
  temperatures, and flurries will continue today.

- Blustery and cold weather will continue through Thanksgiving
  Day.

- Impactful snow is likely Saturday into Saturday night. It
  remains too early for highly specific snowfall amounts and
  locations, but there is a distinct potential for 6"+ amounts
  (and higher end travel impacts) in portions of the area.

- Well below normal temperatures will persist into or through
  next week, perhaps with additional chances for snow (Monday
  night).

&&

.DISCUSSION...
Issued at 256 PM CST Wed Nov 26 2025

Through Thanksgiving Day:

A stout 993 mb surface low continues to traverse across the UP
of MI this afternoon which has generated a very pronounced
pressure gradient across much of the Great Lakes and Upper
Midwest regions. As a result, westerly winds continue to
regularly gust in the 45-50 mph range in northern IL and
northwest IN. While a localized gust up to 60 mph still cannot
be ruled out (mainly near the IL-WI line), it seems the higher
concentration of these gusts should remain in WI. Therefore, we
have opted to maintain the strongly worded Wind Advisory wind
gusts up to 55 mph through 9 PM this evening. Outside of the
wind, the associated upper trough has generated some isolated to
widely scattered snow showers and flurries in WI with of few of
these oozing into northern IL at times. Given the modest
moisture noted in forecast soundings, expect these snow
showers/flurries to be very hit and miss through early evening
before the better moisture and trough pushes east into Lower MI.
Regardless, little to no snow accumulation is expected.

Winds will gradually diminish through tonight as the surface
low continues its eastward propagation. However, gusts in the
30-40 mph range still look to remain through the night and into
Thursday morning. Otherwise, expect cloud cover to also diminish
which will allow temperatures to dip into the lower to mid-20s
overnight. The weather on Thanksgiving will again be on the
chilly side with highs only expected to top out in the lower
30s. Though with continued breezy west-northwest winds gusting
around 30-35 mph temperatures will feel more like the upper
teens and lower 20s despite the partly cloudy skies.

Yack


Thursday Night through Wednesday:

A weak wave shifting SSE across Lake Michigan Thursday evening
will sufficiently lift inversion heights to foster scattered
lake effect snow showers across northern Porter County, with
some flurries from stratus residing in the DGZ across northern
Illinois and the remainder of northwest Indiana in the evening.

The main focus then turns to an increasing potential for a
winter storm with several inches of accumulating snow across the
region Friday night through Saturday. A strong trough currently
approaching the WA/OR coast is progged to dig into the central
Great Plains by early Saturday while phasing with a weak sub-
tropical wave currently over the northern Baja of California.
The combination of modest Pacific moisture from both systems as
well as strong low-level moisture transport through the
mid/lower Mississippi River Valley will yield a sizable shield
of precipitation across the central CONUS. As the phased wave
amplifies Friday night into Saturday morning, robust low-level
WAA/isentropic ascent is expected to bring waves of accumulating
snow across much of the forecast area. While accumulating snow
is expected to continue over the area Saturday afternoon and
night, solutions diverge with the ultimate track of the surface
low as a result in differences in timing of the phasing and
amplification. A somewhat bimodal solution exists in guidance:

1) The wave quickly amplifies and becomes slightly negatively
tilted west of the area, bringing the surface low (and 925hPa)
low well north into the forecast area (northern MO to Chicago
track). This would support lower snow totals for part of the
area as rain possibly mixes with the snow east of I-55 and along
the immediate Illinois shore.

2) The wave strengthens gradually and tracks in a more ENE
direction, producing a surface low that tracks from north of St.
Louis to northern Indiana. This has become a more favored
scenario is guidance over the past 24 hours and suggests precip
will remain primarily all snow for much of the forecast area.

As can be expected, assessing snowfall amounts remains a
challenge with this system owing to the magnitude of QPF (i.e.
rate of amplification of the wave) and variability in snow
ratios (exact track of the low). Focusing solely on QPF,
ensemble systems overwhelmingly depict storm total values in the
0.5-0.75 inch range for nearly the entire CWA. Outlying
members, specifically several within the EPS, indicate QPF over
1". Snow ratios continue to favor around the typical 10:1 values
given the lack of substantial ascent within a shallower DGZ as
well as robust low-level WAA. Putting all this together, it is
feasible that warning criteria snowfall of 6"+ could be met for
much of northern Illinois, particularly northwest of a Chicago
to Mendota line where slightly colder thermo profiles support
modestly higher snow ratios. However, if the southward trend in
guidance persists, higher snow totals may focus south and
include the entire Chicago metro. Given the potential impacts
for travel over the holiday weekend, continue to monitor for
forecast updates and, if necessary, consider adjusting travel
plans.

The main snow shield should quickly exit to the east Sunday
morning, leaving a period of strong CAA and flurries from
shallow stratocumulus. Conditional on the presence of the fresh
snowpack over the weekend, clearing skies and diminishing winds
with an approaching surface ridge will promote a rather chilly
Sunday night with lows potentially at or below zero across
interior northern Illinois. Very cold conditions will persist
through Tuesday as a reinforcing shot of colder air arrives on
Monday. A mid-level wave crossing the Ohio River Valley late
Monday afternoon and Monday night may brush southern portions of
the forecast area with light snow. Sub-zero low will again be
possible Monday night if the aforementioned system remains
solidly south of the area.

Kluber

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1103 AM CST Wed Nov 26 2025

The main aviation concern through the TAF period is a
continuation of strong north to northwest winds as a low
pressure system moves through the Great Lakes. Gusts of 35 to
45 kt will prevail through the evening before ever-so-gradually
decreasing in magnitude through the remainder of the TAF period.
A few snow flurries/showers will continue throughout the day as
well, before ending overnight. Cigs will remain near or just
above MVFR through the TAF period.

Borchardt

&&

.MARINE...
Issued at 245 PM CST Wed Nov 26 2025

Key Marine Messages include:

- Storm Warning continues for the IL and IN nearshores through
  this evening. Gale Warning then continues tonight through
  Thursday evening.

A stout 993 mb surface low continues to traverse across the
Upper Peninsula of MI which has generated a strong pressure
gradient over Lake Michigan. These features have resulted in
frequent 50 kt storm force winds over the lake this afternoon.
While the storm force gusts will gradually subside this evening,
35-40 kt gales are expected to persist through Thursday
afternoon and possibly into the evening hours. Regardless of
wind magnitude, the west-northwest wind directions will
continue to generate dangerous waves up to 10 to 14 ft with
occasional waves up to 18 ft through Thursday especially on the
eastern shores of the lake.

All that said, no changes have been made to the ongoing Storm
Warning which remains in effect until 9 PM this evening and the
Gale Warning that remains in effect until 10 PM Thursday
evening.

Yack

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory until 9 PM CST this evening for ILZ003-ILZ004-
     ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-
     ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-ILZ104-
     ILZ105-ILZ106-ILZ107-ILZ108.

IN...Wind Advisory until 9 PM CST /10 PM EST/ this evening for
     INZ001-INZ002-INZ010-INZ011-INZ019.

LM...Storm Warning until 9 PM CST this evening for the IL and IN
     nearshore waters.

     Gale Warning from 9 PM this evening to 10 PM CST Thursday for
     the IL and IN nearshore waters.

&&

$$

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