923
FXUS63 KILX 120444
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1044 PM CST Thu Dec 11 2025

.KEY MESSAGES...

- A Winter Weather Advisory is in effect for nearly all of central
  and southeastern Illinois 3pm today through 6am tomorrow
  morning. Storm total snowfall will range from 2 to 5 inches.

- Another fast-moving system will bring a healthy dose of snow on
  Saturday. The latest NBM shows a 50-80% chance of greater than 3
  inches of snow for central and eastern IL.

- A surge of bitterly cold air will result in sub-zero apparent
  temperatures Friday night through Monday morning. Sunday morning
  has wind chills of -20 to -30 degrees in the forecast.

&&

.UPDATE...
Issued at 736 PM CST Thu Dec 11 2025

A shortwave disturbance drifting southeast through the Midwest is
bringing accumulating snow to virtually all of central and
southeast Illinois this evening. While lapse rates through the DGZ
are poor, an area of enhanced FGEN at 700mb extending from roughly
Macomb to Mattoon is resulting in sufficient uplift for a band of
moderate snow. Flakes are large due to weak PBL winds, which is
limiting compaction and supporting hourly rates north of 1/2 inch
at times. PoPs, QPF, and hence snow amounts were adjusted in the
forecast to account for this area of persistent moderate snow,
where 4-6 inches is expected by early tomorrow morning. In
addition, surface visibility and radar trends indicated more snow
than anticipated along and immediately south of the initial Winter
Weather Advisory, so we extended that south to include Scott,
Clay, and Richland Counties.

Bumgardner

&&

.DISCUSSION...
Issued at 131 PM CST Thu Dec 11 2025

A clipper system will be moving through this afternoon. Timing is
showing snow onset by 3pm in west central IL. The southern extent
of the 1 inch snow amounts reaches from Hancock County to
Lawrence County. As you move north from there, snow amounts will
increase. The core of the highest snow amounts is forecast to
impact I-74 this afternoon into the overnight hours. We are
expecting snowfall amounts of 2-5 inches across central and
southeastern IL from this event, with the greatest amounts
stretching from Knox County to Vermilion/Edgar Counties. We could
see 0.5 inch to 1 inch per hour rates at times. Winds should
generally be less than 15 mph through the event. Evening commute
and morning commute could be impacted by snow covered roads and
slick spots. Please allow for extra travel time and give extra
space between vehicles.

Another system is expected to move through central IL on Saturday.
The axis of highest amounts is forecast to be a bit further south
than today`s system. When we have training systems like this, they
tend to travel along the gradient of where the snow had fell
previously, when the snow lingers on the ground. An arctic front is
to move through Friday night, which will interact with a fast moving
shortwave, bringing us another healthy dose of snow to central IL.
Snow amounts look very similar to tonight, but further south, with 2-
5 inches forecast. Snow ratios are going to be about 14-16:1 with
this system. The NBM is showing 50-80% chance of more than 3
inches across central to eastern IL, with bullseyes of 40-50%
chances of greater than 5 inches in spots. Chances of more than 7
inches are very low but non-zero, so will be watching trends and
development closely. Another Winter Storm Advisory is looking
likely, with the potential of a warning being issued.

After Saturday`s snow, we will be moving into a drier pattern with
high pressure setting up Sunday morning. Pulling the arctic south to
us this weekend. Dangerously bitter temperatures are expected to
spill into the area Friday night lasting through Sunday night. The
coldest period is late Saturday night to Sunday night. Wind chills
Sunday morning will be around -20 to -30 degrees. Consideration for
Extreme Cold Watches/Warnings is being done but we need to make it
through tonight`s system before getting to that bridge. Single digit
highs are forecast for Sunday. Temperatures will being to rise
Monday morning, with highs in the 20s Monday. By Wednesday, highs
are forecast to be into the mid 40s to low 50s, which will be a
welcome break from the very cold weather we have been
experiencing.

Copple

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1039 PM CST Thu Dec 11 2025

Predominantly MVFR ceilings and IFR visibilities continue this
evening as an area of snow drifts southeast through the region.
While this activity should be tapering to scattered snow showers
between 06-10z, it will leave lingering IFR ceilings and perhaps
some patchy fog in its wake. As the surface low passes to the
south, 4-8 kt winds will slowly back to a northeasterly direction
early Friday morning, but then switch around to the west-
northwest behind a cold front late morning-early afternoon.
Guidance has become a little less optimistic on improvement in
ceilings Friday, especially at SPI, DEC, and CMI, where IFR
conditions are forecast through the end of the period.

Bumgardner

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST Friday for ILZ027>031-
036>038-040>057-061>063-066>068-071>073.

&&

$$