116
FXUS63 KILX 071925
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
125 PM CST Sun Dec 7 2025

.KEY MESSAGES...

- Aside from a brief warm up on Tuesday and Wednesday, below
  normal temperatures are expected. Bitter cold temperatures are
  likely to return late in the week.

- The pattern remains unsettled, with a chance for rain Tuesday
  night (20-50%), perhaps mixing with snow into Wednesday
  morning, and then a chance for light snow accumulations on
  Thursday (20-40% chance of 1").

&&

.DISCUSSION...
Issued at 119 PM CST Sun Dec 7 2025

*** THROUGH TONIGHT ***

A cold front continues to sink south into southern IL Sun
afternoon. Behind the front, a narrow corridor of dense fog is
slowly sinking southeast, with KMTO the latest to drop down to 1/4
mile as of 12pm/18z. Fcst soundings and recent mPING reports
suggest that patchy drizzle is also present. This area of drizzle
with also steadily shift south, mainly occurring in areas south of
I-72 where temps are currently above freezing. Into the evening,
as CAA continues behind the front, a brief changeover to freezing
drizzle is possible near/south of I-70 this evening. However,
ground temps should be a bit warmer and largely stymie any impacts
from occurring, although a few slick spots can`t be ruled out on
bridges or overpasses. Forecast soundings show that the column
continues to quickly cool, favoring a change to some light snow
this evening, again in areas near/south of I-70. Accumulations are
not expected.

Colder air pushes in from the north tonight. Temps across northern
IA are currently in the single digits. Lows tonight will range
from the single digits northwest of Peoria to low 20s south of
I-70. Fetch off Lake Michigan is expected to result in thicker
cloud cover near/east of I-55, which will help keep temps a bit
warmer in those areas tonight (lows in the teens). Temps remain
below normal on Monday, with highs generally in the mid 20s north
of I-70.

*** THIS WEEK ***

The upper pattern remains unsettled, with a series of clipper
waves moving across the northern tier of the US. This will lead
to a weaker sfc low (MSLP greater than 1000 mb) passing north of
IL Mon night, followed by a stronger low (MSLP less than 995 mb)
tracking through southern WI Tues night. These low tracking to our
north will induce southerly sfc winds that moderate temps by
Tues-Wed, with highs ranging from the upper 30s to upper 40s
(coldest north of I-74, warmest south of I-70). The precip
associated with these waves will mainly stay north of the ILX CWA,
but some light rain could occur Tues eve/night with chances
increasing with northward extent (30% chance along I-72, 40-50%
chance north of I-74).

The Tues night low will sweep a cold front into the ILX CWA during
the day Wed, swinging winds from southwest to west-northwest.
Forecast soundings suggest gusty winds as mixing deepens and taps
into stronger winds in the 850-925mb layer. The NBM has a 60-80%
chance of peak gusts of 40 mph, which is supported by the forecast
soundings. There is also weak instability within/above the cloud
layer, so flurries, graupel, or scattered snow showers are all
possibilities Wed morning. Given the strong winds, if this precip
is any heavier than flurries the winds would lead to sharp
visibility reductions. This will be something to monitor in the
coming days.

Another quick-moving clipper is expected to produce a stripe of
light snow somewhere across the Midwest on Thurs. There remains
differences among models as to where exactly this wave tracks, but
with just a 30- 40% chance of exceeding 0.10" of QPF, the snow
that does occur should be on the light side (just a 20-40% chance
of over 1" across central/SE IL). Temps trend cooler late in the
week, with highs back near or below freezing on Thurs, then even
colder on Friday (teens to mid 20s).

*** BITTER COLD RETURNS THIS WEEKEND ***

Teleconnections such as the Madden-Julian Oscillation (MJO), a
sub-seasonal tropical pattern, favor the potential for continued
cold air intrusions into the Midwest/eastern CONUS over the next
few weeks. The MJO has been in Phases 7-8 recently, which favors
colder than normal temps over the Midwest/eastern US, and that has
been the case. Most ECMWF Ens members keep the MJO in the Phase
7-8 through the next two weeks, albeit in a less amplified state
than previous weeks so it`s impact on the mid-latitude conditions
may become somewhat less pronounced. There is also an existing
snow pack across the northern Plains and portions of the Midwest,
with more clipper systems set to produce additional snows in some
areas. This snow pack means that additional cold air surges from
the north will be able to stay colder than if there were no snow.

All of this is to say, below normal temps remain favored over
much of the next two weeks, including some periods of bitter cold.
Over the next week, the coldest conditions are expected Fri night
through Sat night, as a very strong sfc high (~1050 mb) over the
far northern Plains helps push bitter cold air south. Backward
trajectories from the GFS indicate this airmass will have Arctic
origins. Lows are expected to drop into the single digits area-
wide both nights, highs are unlikely to reach 20 degF on
Sat. Moderate NW winds (10-15 mph) Fri night could push wind
chills near advisory criteria (15 degF below zero or colder)
north of I-70. There is a 30% chance of reaching cold weather
advisory criteria along the I-70 corridor, increasing to a 60-70%
chance north of I-74.

Erwin

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1118 AM CST Sun Dec 7 2025

Low ceilings of 500 feet or less continue over much of central
Illinois late morning, but conditions have improved to MVFR near
KPIA and the Illinois River valley. While some clearing has taken
place upstream, it has begun to fill in once again. KPIA stands
the best chance of getting into VFR range this afternoon, while
the general trend will be for most improvement across central
Illinois to be during the evening. However, visibility should be
significantly improved by mid afternoon.

Gusty north winds will continue behind a cold front through the
afternoon, but winds become light and variable early Monday.

Geelhart

&&

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

$$