597
FXUS63 KLOT 220903
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
303 AM CST Sat Nov 22 2025

.KEY MESSAGES...

- Another period of rain expected (>80% chance) across the area
  late Monday into early Tuesday.

- A modest warming trend is expected into early next week before
  temperatures turn much colder for Thanksgiving.

&&

.DISCUSSION...
Issued at 303 AM CST Sat Nov 22 2025

Primarily dry and seasonably mild weather (with more sunshine)
is expected for the weekend, owing to an area of surface high
pressure shifting across the mid-section of the country. As
this surface ridge axis passes southward across the area this
morning, surface winds will turn southwesterly. The associated
influx of a warmer airmass will thus support warmer temperatures
today, with afternoon readings topping out in the low 50s for
most locations under partly cloudy skies. A weak cold front will
shift across the area into early this evening, but only a brief
increase in mid-level cloud cover and a westerly wind shift is
anticipated in our area as result of its passage. With no push
of cold air expected with this front, we will be set to have
another nice late November day for Sunday. Mainly sunny skies
through the day should support highs in the low to mid 50s.

Conditions will remain seasonably mild Monday and Tuesday, but
a period of widespread light soaking rainfall is expected late
Monday into Tuesday morning (highest chances of 80%+ Monday
evening and night). Forecast confidence remains high with this
period of rain, owing to continued very good model and ensemble
agreement with the east-northeastward ejection of the upper low
currently located just off the Baja California coast. This
feature is slated to move out across the Mid-Mississpi Valley
region into the Lower Great Lakes into Tuesday morning.

Following quickly on the heels of this system, another quick
moving northern stream impulse is expected to dig in across the
western Great Lakes by midweek. As it does, surface low pressure
will deepen and consolidate to our north across the Upper Great
Lakes, with an associated strong east-southeastward surging
cold front likely to move across our area sometime Tuesday
night. While this does not look to be a good precipitation maker
for our area on Wednesday (though flurries or intermittent
light snow showers may occur), strong cold air advection is
expected on gusty northwesterly winds (possibly gusting in
excess of 40 mph for a period). This will set the stage for a
turn towards much colder weather for the second half of the
week, including on Thanksgiving Day. High temperatures are
current forecast to only be in the low to middle 30s with wind
chills in the teens and 20s.

Beyond Thanksgiving, signs continue to point to a turn towards
a much more active weather pattern across the central CONUS
going into the first part of December. Ensemble guidance during
this period continues to favor building heights (increased
ridging) across the north Pacific into Alaska (negative Eastern
Pacific Oscillation). Teleconnections related to this pattern
should in turn favor a shift towards an increasingly amplified
downstream upper-level pattern across North America, with deep
troughing over the western CONUS and enhanced ridging in the
eastern and southeastern CONUS. Forecast specifics this far out
for a certain area remain largely unclear. However, it is
certainly a noteworthy larger scale pattern shift that will need
to be monitored for potentially impactful weather systems
affecting the central CONUS during the latter part of the
holiday weekend into next week.

KJB

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1046 PM CST Fri Nov 21 2025

Forecast concerns include...

Patchy/shallow ground fog overnight.
Wind shift to northwest Saturday night.

Showers currently south of the terminals will continue moving
away from the area late this evening with dry conditions
expected through the period.

Some patchy or shallow ground fog is possible overnight into
early Saturday morning for areas away from Chicago. Confidence
remains low with the best chance for fog possibly favoring areas
well south of the terminals, but have maintained light/shallow
ground fog mention at RFD/DPA/GYY.

Light north/northwest winds are expected to become variable
overnight and then shift to the south/southwest Saturday morning
with speeds increasing to 10kt by midday. Speeds may increase
further to 10-15kt in the mid/late afternoon which may continue
into Saturday evening, along with some periodic higher gusts.
Wind directions will shift to the northwest later Saturday night
when a few gusts will also be possible. cms

&&

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

&&

$$

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