305
FXUS63 KILX 301741
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1141 AM CST Sun Nov 30 2025

.KEY MESSAGES...

- Another round of accumulating snow will impact the area by
  Monday evening. There is currently a high (50-70%) chance of
  exceeding 3 inches of snow in areas north of a Taylorville to
  Champaign line. At least minor travel impacts are anticipated.

- We are entering a prolonged period of cold weather this week.
  Daily temperatures will average 15 to 25 degrees below what is
  considered normal for this time of year. Cold weather impacts
  are likely.

&&

.DISCUSSION...
Issued at 558 AM CST Sun Nov 30 2025

Early this morning, gusty northwest winds are impacting central
Illinois, situated between a departing winter storm (1007 mb) over
lower Lake Michigan and a strong 1040 mb surface high building into
the Northern Plains. Our regional mesonet has recorded gusts of 35-
45 mph, with a few reaching 50 mph. Boundary layer winds appear to
be mixing deeper than model forecasts, a trend that may continue
past sunrise.

While a short-fused Wind Advisory was considered, an SPS was issued
instead, as only a few locations met the advisory criteria. Winds
will stay breezy this afternoon, generally 20-30 mph, but will ease
as a secondary trough moves across the Corn Belt, pushing the winter
storm further eastward into the Great Lakes. Anticipate low clouds
and scattered snow showers near and north of I-74 into the early
afternoon as this trough axis crosses into northern Illinois. Winds
will then diminish this evening as the trough departs and high
pressure moves into the Midwest.

Our focus quickly moves to Monday afternoon, when central Illinois
is expected to see another burst of accumulating snow. This snowfall
will be driven by a strengthening band of frontogenesis (FGEN)
beneath a pair of phasing jet streaks. While the resulting upward
motion (ascent) will be robust, it will also be brief. Model
guidance, both ensemble and multi-model, suggests Quantitative
Precipitation Forecast (QPF) values between 0.1 and 0.3 inches for
our region. With an estimated Snow-to-Liquid Ratio (SLR) near 15:1,
the expected snowfall accumulation is 2 to 4 inches, which will
likely necessitate a Winter Weather Advisory for a good chunk of the
area.

Temperatures will fluctuate between very cold and just plain cold
throughout the week as high pressure moves in and out of central
Illinois. A brief warm-up is expected Wednesday afternoon, bringing
the next chance for a good portion of the area to rise above
freezing. This warming trend is due to a southwest wind shift ahead
of a weak cold front approaching from the north. This frontal
passage may bring a few snow showers, though accumulations are
expected to be limited to a dusting. Following the front, a short
period of very cold temperatures will settle in, with high
confidence in overnight lows dipping into the single digits both
Wednesday and Thursday nights. While a Cold Weather Advisory is
currently unlikely, wind chill values are still anticipated to fall
below zero.

Another potential winter storm is on the horizon to conclude the
week, driven by a mid-level trough lifting and pivoting across the
Southern Plains. It`s not yet clear whether we will be completely on
the cold side of this one, or somewhere in the messy middle, but it
does look like enough Gulf moisture will be juiced into this system
to cause some sort of winter-weather impacts near or just south of
our area.  For what it`s worth, both ensemble and multi-model
guidance support a 1 in 5 chance of snowfall exceeding 2 inches
across our area by Friday night. This same guidance also supports a
low probability of freezing rain as well.

MJA

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1141 AM CST Sun Nov 30 2025

Northwest winds will become light and variable this evening as
surface high pressure slides overhead. MVFR stratus looks to improve
to VFR overnight before dropping back below 3k ft with our next
approaching system late Monday morning. Some guidance has keyed in
on an area of shallow fog developing late tonight near/south of the
I-72 corridor, but probabilities of it falling below 3SM is fairly
low (20-30%).

NMA

&&

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

$$