454
FXUS63 KILX 030841
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
241 AM CST Wed Dec 3 2025

.KEY MESSAGES...

- Widespread flurries and patchy freezing drizzle begins early
  this afternoon. Only limited travel impacts are anticipated, but
  there could be a few slick spots wherever wintry precip becomes
  focused. Drive with caution, especially during the afternoon and
  evening commute.

- The coldest air of the season so far will arrive tonight and
  last through Friday morning. Take immediate steps to protect
  people, pets, and pipes from the cold.

&&

.DISCUSSION...(through next Tuesday)
Issued at 239 AM CST Wed Dec 3 2025

A good surge of warm air advection is currently underway early
this morning. This is due to surface winds shifting southerly as
surface high pressure departs. As a result, temperatures are
expected to slowly climb into the lower 30s this afternoon, ahead
of an approaching cold front.

A decent signal persists for wintry precipitation to develop
behind the front by early afternoon. This is linked to a
sharpening 700 mb Frontogenetic (FGEN) band beneath a pair of
phasing jet streaks aloft. The latest HREF guidance places the
greatest chance (30-50%) for PoPs along the I-70 corridor around
00z, where wet-bulb temperatures are cold enough to support snow.

The main challenge is a particularly non-uniform vertical
moisture profile, with cloud ice present in some areas but absent
in others. This creates a precipitation type (p-type) challenge,
making both snow showers and freezing drizzle plausible. HREF QPF
LPMM still suggests a range of a trace to 0.10 inches, with the
higher end most likely where the FGEN band develops, and the lower
end elsewhere.

In total, this points to widespread flurries and patchy freezing
drizzle, with the potential for a narrow stripe of light
accumulating snow. Our base case forecast calls for a skift of
wintry precipitation in most areas, but up to one inch of new snow
accumulation is possible (10% chance) along or near the I-70
corridor this evening.

The region then braces for the coldest air of the season so far,
arriving behind the arctic front and lasting from tonight through
Friday morning. This exceptionally cold spell for early December
will bring temperatures about 25-30 degrees below average.
Overnight lows will plummet to the single digits, and daytime
highs will struggle to reach the teens, especially north of I-70.
Additionally, wind chill values in our northern areas are expected
to approach advisory criteria both tonight and Wednesday night.

Marginally warmer and dry weather is expected to persist into the
end of the week, as the storm system previously of concern for
Friday remains forecast to pass to the south. However, a signal
for light accumulating snow returns this weekend. This is
attributed to a clipper-like system moving across the Corn Belt,
driven by a choppy northwest flow. The latest guidance from the
NBM and Grand Ensemble (GEFS, GEPS and EPS) currently gives a low
(less than 20%) chance for at least one inch of snow, though this
probability may be understated due to existing differences in
timing among the models.

The extended forecast suggests a potential warm-up by the middle
of next week. This is due to a longwave ridge settling over the
western US, which will bring warm, downslope flow across the
Plains, eventually advecting into the Midwest. During this period,
a series of clipper systems are expected to track across the
Upper Mississippi Valley into the Great Lakes, potentially grazing
our northern forecast areas at times.

MJA

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1042 PM CST Tue Dec 2 2025

Late this evening and overnight, MVFR/IFR stratus mainly between
007-011 persists along and east of I-55 but should slowly
continue to erode overnight into Wednesday morning. SSW winds
around 9-12 kt are expected overnight, then will slowly veer to
the west then northwest during the afternoon as a slow moving cold
front sags into the region. MVFR/IFR ceilings will return along
and behind the cold front, and there is a chance (30%) for light
precip with the front. There remains uncertainty on the precip
type, but both snow and drizzle will be possible with surface
temps hovering near the freezing mark much of the afternoon.

Deubelbeiss

&&

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

$$