931
FXUS63 KLOT 232030
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
230 PM CST Sun Nov 23 2025

.KEY MESSAGES...

- Increasing low-level cloud cover late tonight into Monday
  morning, with locally dense fog possible south of I-80.

- Light rain or drizzle Monday night into early Tuesday.

- Turning cold and blustery Wednesday with wind gusts > 35 mph,
  potentially paired with a few flurries.

- Unseasonably cold temperatures (highs in the 30s) continue on
  Thanksgiving and through the end of the week, with wintry
  precip becoming increasing likely next weekend.

&&

.DISCUSSION...
Issued at 230 PM CST Sun Nov 23 2025

A broad surface high centered over southern Illinois has
yielded a sunny and seasonably mild day across the region, with
mostly clear skies remaining through the evening amid light SSW
winds.

A persistent band of thick stratus from central Missouri to
western Kentucky today will become a focus tonight and
especially Monday as low-level moisture advection takes hold
across the mid-Mississippi River Valley. Expectations are for
the stratus to expand NNE under a developing shallow inversion
from ongoing WAA. Added weak isentropic ascent within and below
this inversion should bring low stratus (possibly LIFR ceilings
and locally dense fog) into at least southwest portions of the
CWA prior to daybreak, and possibly across the entire CWA by
mid-morning. Where the northern edge of the stratus resides by
this time will dictate temp trends as diurnal erosion of the
clouds is likely given the expected shallow cloud depth. But
with thickening cirrus also spreading northward through the day,
erosion of any cloud cover will be notably slower than what was
observed farther south today. Have maintained a somewhat middle
ground with max temps in the upper 40s on Monday, but thick
stratus would support temps in the low to mid 40s and little
stratus would favor highs in the mid 50s.

Continued low-level WAA and some diurnal heating below
mid/upper-level diffluence will lift and weaken the low-level
inversion late in the day and especially Monday night into
Tuesday morning, which will support at least some areas of light
rain or drizzle for most locations. However, a disjointed
placement up the main upper-level trough crossing southern
Wisconsin and the mid-level wave crossing the south half of
Illinois may result in a minimum of precip coverage and QPF
across most of northern Illinois during this period.

A potent cold front will then sweep across the area Tuesday
evening, ushering in much colder and blustery conditions
overnight through Wednesday. A modest isallobaric component
mostly aligned with the gradient flow combined with added
diurnal mixing will support the potential for wind gusts nearing
wind advisory criteria (gusts of at least 45 mph) on Wednesday.
Additionally, the depth of expected stratocumulus should be
sufficient for isolated to scattered snow showers (or at least
flurries) in the morning and possibly into the afternoon. Cold
and somewhat blustery conditions will persist for Thanksgiving
Day, with the incoming cold airmass suggesting that max temps
both Thanksgiving and Friday will struggle to rise much above
freezing each afternoon.

Kluber


A much more active weather pattern will take hold across the
central CONUS this weekend and into the first week of December.
Overall, the larger scale pattern across North America continues
to favor upper troughing setting up across the western CONUS
and upper ridging across the southeastern CONUS during this
period. The presence of greatly enhanced southwesterly mid and
upper level flow into the lower Great Lakes in such a pattern is
notorious for steering numerous impulses across our region.
Accordingly, some periods of active weather, with rain and/or
snow is possible as we head into next weekend. Ensemble
solutions have steadily zoned in on a late Saturday into Sunday
period for potential wintry precip, including accumulating snow.
It is important to note that while the pattern looks
increasingly active, the finer scale details this far out remain
largely unclear and will need to be ironed out in the coming
days. For example, the potential wintry weather next weekend
will depend on phasing of a trough currently just east of the
Kamchatka Peninsula (that will also have to round the Aleutian
Low) and another trough halfway between Hawaii and California.
Nevertheless, this period will be monitored closely for
potentially impactful weather systems across the central CONUS
that could impact holiday travel. Stay tuned.

KJB/Kluber

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 1209 PM CST Sun Nov 23 2025

Key Messages:

- There is a potential for low ceilings and visibilities
  tomorrow, though there is high uncertainty in the occurrence
  and duration of any sub-VFR conditions.


There are no forecast concerns through the remainder of the
daytime hours today and most of tonight with VFR conditions
prevailing and winds largely remaining under 10 kts. There are
concerns for late tonight through tomorrow, however, as a plume
of low-level moisture lifts northward into the ZAU airspace.

Much like what was seen this morning across most of central and
southern Illinois and the Ozarks, this moisture plume will
likely feature an expansive blanket of IFR/LIFR stratus and fog
as it approaches the Chicago and Rockford metro areas tomorrow
morning. However, it remains uncertain whether this stratus and
fog will reach our TAF sites or whether it will remain just
south of the terminals. Forecast guidance remains split on which
scenario to favor, so did not have enough confidence to steer
the TAFs one way or another with respect to ceilings and
visibilities and have thus maintained a "middle ground"
approach in the 18Z TAFs.

The other point of forecast uncertainty is how long the
stratus/fog persists tomorrow if it does end up overspreading
the terminals late tonight/early tomorrow morning. Would again
think that things would play out similar to what happened to
our south today with the stratus and fog eroding by midday along
the periphery of the low-level moisture pool (where the stratus
deck is thinnest) and persisting through most or all of the day
elsewhere. Elected to advertise a more pessimistic scenario in
the TAFs with respect to the duration of the sub-VFR conditions,
but again, confidence that this will ultimately turn out to be
the case is still fairly low at this time.

Ogorek

&&

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

&&

$$

Visit us at weather.gov/chicago