685
FXUS63 KILX 110035
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
635 PM CST Wed Dec 10 2025

.KEY MESSAGES...

- 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, with a 20-40% chance for greater than 4 inches
  of snow along I-74.

- 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 629 PM CST Wed Dec 10 2025

An area of light snow showers has developed across eastern Iowa
and northwest/west-central IL, beneath a 700-400mb differential
(positive) vorticity advection (DPVA) maximum. This is spreading
slowly towards the east-southeast, and based on radar trends may
extend into portions of central/east-central IL - though it will
have quite a bit of dry air to erode (per the 00z ILX raob) as it
does so. Upstream visibility observations have been mostly
unaffected, though a few drops into the 3-5 mile range have been
reported. Most locations shouldn`t see anything measurable, but
locally up to a half inch seems reasonable based on output from
the few CAMs which caught onto this activity. No model has done a
great job of highlighting the location of this snow, so we needed
to extrapolate based on radar for our increased PoPs - highest
along roughly the I-74 corridor through 1am.

Bumgardner

&&

.SHORT TERM...  (Tonight Through Late Thursday Night)
Issued at 241 PM CST Wed Dec 10 2025

Light snow, with little to no accumulations, will linger across
northern areas of the CWA this evening, mainly along and north of I-
74. Then, after a brief dry period, Thursday morning, a stronger
clipper system will plunge into the area for Thursday afternoon
through Thursday night. All models have trended southwest of I-74
with the axis of the heaviest snow band; however, the NAM keeps it
along I-74. Blend of models also shifts the axis southwest and this
trend was followed for this forecast package. Typical with many
clippers, decent warm air advection ahead of the system will provide
ample moisture to work with and there will be sufficient isentropic
lift along and north of the low track; which should result in decent
amount of snowfall across most of central IL, with the heaviest
snowfall occurring Thur evening. Snow should begin in the west Thur
afternoon with 1-2 inches possible by 6pm northwest of I-55. Snow
will continue to the east and southeast with 2-3 inches possible
during the evening hours across areas north of a Macomb to Robinson
line. If the forecast track remains the same through tonights
models, then a winter weather advisory is likely for tomorrow
afternoon through tomorrow night. There appears to be a 50-80%
chance of amounts being over 2 inches, with even a 20-40% chance of
amounts exceeding 4 inches along I-74. The probabilities could
increase, as long as models remain consistent the next 12 hours.

P-type will primarily be snow. However, forecast soundings southwest
of Springfield and south of Effingham show small possibilities of
brief periods of rain or freezing rain mixing with the snow during
the late afternoon or early evening. Do to the high uncertainty and
low probability of the freezing rain occurring, will not have it in
the forecast at this time.

Temperatures will remain below freezing through tomorrow night,
across all areas except for southeast IL.

Auten

.LONG TERM...  (Friday through Next Wednesday)
Issued at 241 PM CST Wed Dec 10 2025

Another clipper system will quickly push through Saturday, which
could lay down another 2-3 inches of snow. However, the bigger
concern will be the extremely cold temperatures for the weekend.
Coldest temperatures will be Saturday night and Sunday night, with
air temperatures below zero across most of the CWA. Combined with
the winds and wind chills of 15 to 25 below zero will be common Sat
night, with wind chills around 15 below for Sun night.
Fortunately, dry weather is expected Sunday through the beginning of
next week. The other good news is the bitter cold temps will be
short lived as temperatures will begin to significantly warm with
temps reaching above freezing on Tuesday and in the 40s for by
Wednesday.

Auten

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 549 PM CST Wed Dec 10 2025

MVFR ceilings will continue for most of the forecast period as
cyclonic flow continues beneath an expansive upper level trough.
Winds will continue to ease this evening as the surface gradient
slackens, with the primary aviation concern shifting to light snow,
especially for PIA and BMI where confidence was high enough to
include a mention in a PROB30 group. Upstream observations suggest
this is mostly resulting in MVFR visibilities, but HREF guidance
does advertise some notable (30-50%) probabilities for both IFR
ceilings and visibilities, so we`ll need to watch closely through
the evening.

Ceilings may (40% chance) break up or lift above the MVFR
category briefly late tomorrow morning into the early afternoon,
but this will be short-lived as another disturbance dives
southeast into the area by mid afternoon - lowering ceilings and
reducing visibility via snow (or a rain/snow mix for SPI and DEC).
Confidence is medium-high (50-70%) in IFR conditions by the end
of the forecast period, especially at the I-74 corridor terminals
(i.e., PIA, BMI, and CMI).

Bumgardner

&&

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

$$