997
FXUS63 KILX 101627
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
1027 AM CST Wed Dec 10 2025

.KEY MESSAGES...

- Strong northwesterly winds gusting 40-50 mph will accompany
  scattered rain and snow showers this morning.

- Snow will spread across much of central Illinois Thursday
  afternoon through Thursday night. There is a 50-80% chance for
  greater than 2 inches of snow along and northeast of a Macomb to
  Robinson line.

- Another surge of very cold air is expected by the end of the
  week...resulting in sub-zero apparent temperatures Friday night
  through Monday morning.

&&

.UPDATE...
Issued at 1027 AM CST Wed Dec 10 2025

Precipitation continues to move southeast across the CWA this
morning. Precip starts as rain and then transitions to snow. Radar
shows a nice band of heavier snow, currently located near I-55,
that will bring vis down as it moves through. Also, back edge of
the snow has entered northwest IL and would expect this to move
through the CWA this afternoon. So, continued forecast for rain
changing to snow, today with a quick burst of heavier snow with
minor accumulations expected. Northwest winds will also remain
gusty with peak gusts of 35-40+ in eastern IL. Will keep wind
advisory going until these stronger gusts leave the state. Only
minor updates made to pops/wx so not planning on any further
updates until the wind advisory expires at noon.

Auten

&&

.DISCUSSION...
Issued at 334 AM CST Wed Dec 10 2025

...Strong Winds This Morning...

08z/2am surface analysis shows a pre-frontal trough approaching
the Illinois River...with a cold front noted further upstream
across northern portions of Iowa/Nebraska. Once the trough swings
through the area, winds will veer to northwesterly and gust
30-40mph for the entire day. The main concern for higher gusts
sill focuses on scattered rain/snow showers along and just behind
the cold front. Models have backed off somewhat on the magnitude
of the gusts, as winds at the top of the mixed layer are generally
less than 50mph. Still think the showers will be able to mix some
of the momentum down to the surface resulting in occasional gusts
in the 40-50mph range through midday. A Wind Advisory remains in
effect for much of central Illinois accordingly. Surface
temperatures will initially be in the upper 30s and lower 40s
early this morning, but will drop into the lower to middle 30s as
the scattered showers arrive. The snow may temporarily cut
visibilities to less than 1 mile in a few spots and will likely
result in a dusting to a couple tenths of an inch on grassy
surfaces. The most widespread/significant snow showers will push
into Indiana by midday, followed by just flurries for the
remainder of the afternoon and evening.

...Snow Late Thursday...

00z Dec 10 models continue to have difficulty pinning down the
exact track of the next approaching clipper system, which is
evident on latest water vapor imagery over British Columbia. Since
the system is now on land, it will be much better sampled by both
surface and upper air observations...thus the next model cycle
should have a much better handle on the exact details. Presently
there are two distinct camps...the synoptic models such as the
ECMWF and GFS which take the system across the heart of central
Illinois and the higher-res models such as the NAM and HRRR that
track it a bit further north. Taking the middle-of-the-road model
consensus places the axis of heaviest snowfall generally along the
I-74 corridor...but this could be shifted slightly northward if
the CAMs continue their trends. As it stands right now, it appears
snow will develop across the Illinois River Valley by mid-afternoon,
then quickly spread eastward toward I-57 by sunset. The
heaviest/steadiest snow will occur during the evening, with the
precip shifting eastward and diminishing overnight. The 00z Dec 10
LREF now shows a high probability (50-80% chance) for greater
than 2 inches of snow along/north of a Macomb to Robinson line.
Given the northward shift in the track, an elevated warm layer
could lead to mixed precipitation along the S/SW edge of the main
snow band. This looks most likely to occur along/southwest of a
Rushville to Taylorville line where the latest forecast includes a
mix of snow and freezing rain.

...Bitterly Cold Conditions This Weekend...

As has been advertised for the past several days, another surge of
extremely cold air will arrive this weekend. A short-wave trough
interacting with the baroclinic zone will bring another round of
light snow to central Illinois on Saturday: however, it is still
too early to pinpoint exact accumulations. The main weather story
will be the sharply colder conditions after FROPA. High temperatures
will drop from the 30s on Friday into the single digits and teens
by Sunday. While wind-chill values will dip below zero across
parts of the area by late Friday night, the coldest period will be
Saturday night into Sunday when apparent temperatures will approach
or exceed the -15F advisory criteria everywhere north of I-70.
The extreme cold will begin to ease by Monday as boundary layer
flow becomes S/SW and afternoon temperatures rise back well into
the 20s and perhaps lower 30s in some spots.

Barnes

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 548 AM CST Wed Dec 10 2025

MVFR conditions will prevail through the entire 12z TAF period.
W/NW winds will gust to around 30kt for much of the day...with a
period of wind gusts potentially up to 40kt occurring as scattered
snow showers currently upstream across northeast Iowa pivot into
the area. Based on radar trends and latest obs, think most of the
snow showers and the lowest associated visbys will graze the I-74
terminals between 15z and 19z. Have lowered visbys to 1-2 miles at
those sites accordingly. Further S/SW at KSPI and KDEC, opted to
only carry VCSH with little to no visby restriction. The snow
will quickly exit into Indiana by early afternoon, with little
more than scattered flurries anticipated for the rest of the
afternoon into the evening. NAM/HRRR forecast soundings show the
MVFR cloud deck persisting through Thursday morning. Winds will
begin decreasing by late afternoon, then will drop to 12kt or less
after 03z/04z.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until noon CST today for ILZ027>031-036>038-
040>045-047>056-061-062-066.

&&

$$