370
FXUS63 KILX 022052
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
252 PM CST Tue Dec 2 2025

.KEY MESSAGES...

- Bitterly cold conditions will arrive Wednesday night through
  Thursday night...with potentially record-breaking low
  temperatures at or slightly below zero by Friday morning.

- A fast-moving system will bring another period of light snow to
  the region this weekend. The 12z NBM indicates a 20-30% chance
  of snowfall exceeding 1 inch along and north of a Macomb to
  Tuscola line.

&&

.SHORT TERM... (Tonight through Wednesday)
Issued at 252 PM CST Tue Dec 2 2025

As high pressure shifts into the Ohio River Valley and boundary
layer winds become southwesterly, the persistent low cloud cover
that has plagued central Illinois today will gradually begin to
erode from SW to NE tonight into Wednesday morning. At the same
time, the slightly warmer air advecting over the cold/snow cover
will likely lead to fog development...especially east of I-55.
While CAMs are not particularly bullish with visby reductions, the
HRRR/RAP/GFSLAMP all hint at fog across the E/SE KILX CWA. Given
what happened last night into this morning, have opted to include
fog mention everywhere along/east of I-55 accordingly. After any
early morning fog dissipates, SW winds will continue to bring
milder air into the region...resulting in afternoon highs climbing
above freezing. The warmest readings will be across Clay,
Richland, and Lawrence counties where the snow cover is thinnest
and where partial sunshine will occur...leading to readings
climbing into the upper 30s. By afternoon, a strong cold front
will approach from the northwest. Given the lack of deep-layer
moisture, am not expecting much precip with FROPA late Wednesday
afternoon/evening. Will carry chance PoPs for a few snow-showers
along/north of I-72 during the afternoon...then along/south of
I-70 Wednesday night. Little to no snow accumulation is expectd.
Once the front passes, winds will veer to northwesterly and
temperatures will plummet into the single digits north of I-70 and
into the teens south of I-70 by Thursday morning.

Barnes

.LONG TERM... (Thursday through Next Tuesday)
Issued at 252 PM CST Tue Dec 2 2025

Canadian high pressure will settle into the Midwest on Thursday,
bringing decreasing winds and plenty of sunshine. However with the
heart of the cold airmass overhead, high temperatures will
struggle to rise through the teens over the snow cover. Radiational
cooling Thursday night will lead to the coldest readings of the
winter season thus far. The latest guidance suggests lows bottoming
out in the single digits everywhere north of I-70...with a few
spots dropping below zero north of I-72. If these projected
numbers are realized, record lows for December 5 will be broken at
Peoria, Lincoln, and Springfield.

The extreme cold will be short-lived however, as temperatures
quickly moderate back into the upper 20s and lower 30s for the
remainder of the forecast period. Will need to keep an eye on a
pair of weak systems that will skirt through the region during
that time. The first is slated for late Saturday into Sunday,
while the second will be in the vicinity by late Monday/Tuesday.
Models have not resolved either system very well at this
point...with the 12z ECMWF showing the first wave pushing into
central Illinois on Sunday...and the GFS taking the track further
south across Missouri into southern Illinois. Given the high
degree of track uncertainty, have only mentioned low chance PoPs
(20-40%) Saturday night into Sunday. As an early projection, the
12z NBM shows a low probability (20-30% chance) of over 1 inch of
snow along/north of a Macomb to Tuscola line. This will likely be
changed as the track forecast becomes better defined over the next
couple of days.

Barnes

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1150 AM CST Tue Dec 2 2025

Low clouds continue to blanket central Illinois late this morning.
Most terminals have improved to low MVFR: however, both KBMI and
KCMI are hanging on to IFR. 1730z/1130am satellite imagery shows
the back edge of the overcast advancing eastward across Iowa/Missouri
to the Mississippi River. While satellite trends appear optimistic
for clearing across west-central Illinois this afternoon, both
NAM and HRRR forecast soundings suggest the clearing line will
slow substantially...and may not reach KPIA until around 02z...and
not to KCMI until perhaps 14z/15z Wed. Winds are presently light,
but will back to SW and increase tonight as a cold front approaches
from the northwest. Once the SW flow commences, the low clouds
will finally get shoved out of east-central Illinois by late morning
Wednesday. As WAA increases over the fresh snow cover, fog will
become a concern tonight...particularly east of the I-55 corridor.
CAMs are most aggressive with lowered visbys further east in
Indiana: however, based on what happened last night into this
morning, think fog will develop further west than the models
indicate. As a result, have lowered visbys to around 4 miles at
KDEC and 2 miles at KCMI between 09z and 13z. Once the low
clouds/fog clear the eastern terminals, VFR conditions are
expected across the board through midday before the approaching
front brings lower clouds and scattered snow-showers by Wednesday
afternoon/evening.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$