739
FXUS63 KILX 070917
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
317 AM CST Sun Dec 7 2025

.KEY MESSAGES...

- A very light wintry mix along/north of the I-74 corridor will
  come to an end this morning...with no significant travel impacts
  expected.

- The next potential for frozen precipitation will come into the
  picture on Thursday when a weak system will bring a 30-50%
  chance for light snow.

- Another surge of very cold air is expected by the end of the
  week...resulting in sub-zero apparent temperatures by Friday and
  Saturday.

&&

.SHORT TERM... (Today through Monday)
Issued at 317 AM CST Sun Dec 7 2025

08z/2am surface analysis shows a 1011mb low over southeast
Iowa with widespread light to moderate snow occurring along/north
of the I-80 corridor. Further south, precipitation is much
lighter across central Illinois...with most locations along/south
of I-72 remaining dry thus far. As the low tracks slowly eastward,
a mix of light snow/freezing drizzle will gradually come to an
end across the northern third of the KILX CWA by mid-morning.
Given temperatures hovering near 32F across this area, cannot rule
out scattered slick spots on bridges, overpasses, and untreated
surfaces: however, no major travel hazards are anticipated.
Further south, temperatures have risen above freezing and the main
weather story will be fog/drizzle. 08z/2am obs show visibilities
ranging from 2-5 miles east of the I-55 corridor. CAMs appear to
be a bit too aggressive in developing dense fog across this area
over the next few hours: however, think areas of fog will persist
across the E/SE CWA through the morning before the low tracks
further east and gradually pulls a cold front through central
Illinois. Some locations south of I-70 will see fog persisting
into the evening before visibilities finally improve later
tonight. Once the front passes, a colder airmass will settle back
into the region...resulting in overnight lows ranging from the
single digits northwest of the Illinois River around Galesburg/Macomb
to the middle 20s south of I-70. After a cloudy start to the day,
partial sunshine will return by Monday afternoon. Despite the
sun, high temperatures will remain well below normal for this time
of year in the middle to upper 20s north of I-70 and in the lower
30s to the south.

Barnes

.LONG TERM... (Tuesday through Saturday)
Issued at 317 AM CST Sun Dec 7 2025

The next short-wave trough embedded within the prevailing
northwesterly flow pattern will approach central Illinois on
Tuesday. As boundary layer flow becomes S/SW ahead of the wave
and its associated surface low, temperatures will rebound into
the lower to middle 40s. All models track the low well north of
the region across the Upper Midwest Tuesday night into Wednesday,
ensuring mild conditions with any resulting precipitation in
liquid form. Models have been trending drier south of the low
track for the past few runs, so have focused the highest PoPs
(40-60%) along/north of I-74 Tuesday night.

Once the the system passes, a colder airmass will return by
Wednesday night into Thursday. There is still considerable model
disagreement concerning one or more short-wave troughs dropping
into the region by the end of the week. The 00z GFS continues to
show a wave spreading light snow into central Illinois on
Thursday...while the ECMWF/GEM keep the snow mainly off to the
W/SW across Missouri. Given the degree of model spread at that
time range, confidence remains low for snow on Thursday. Will
maintain the current NBM PoPs, but think these will need to be
adjusted as model solutions converge over the next day or two.
Regardless of the Thursday snow chances, the main story by the end
of the week will be the colder weather. While the degree of the
cold varies among the operational models, confidence is growing
that the Friday through next Sunday time frame will be quite cold.
In fact, the 00z Dec 7 LREF shows a 40-70% chance of apparent
temperatures dropping below -10F everywhere north of I-70 by
next Saturday morning.

Barnes

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1112 PM CST Sat Dec 6 2025

Challenging aviation forecast for all sites next 24hrs. VFR
conditions will start all sites, but MVFR cigs will arrive as a
mix of fzdz and snow arrives at most sites. SPI is the only site
that will see only rain through the period when precip is expected.
BMI and PIA will have winter mix of snow, sleet, and freezing rain
overnight, but should transition to a mix of rain and snow toward
morning. DEC and CMI will also see winter mix or fzdz/sn, but
change to ra/sn mix toward morning, followed by drizzle and snow
mix in the morning. IFR cigs/conditions will also arrive over
night with the precip from the west. However, very low cigs and
vis have begun to advect northward from the south and will affect DEC,
CMI and BMI prior to the precip and during the precip. Once
precip ends tomorrow late morning, IFR & LIFR cigs will continue
tomorrow afternoon, but as the front moves through, clouds will
scatter out at PIA and BMI. Scattering out of clouds is possible
at SPI, DEC, and CMI, but confidence is low and would prefer to be
somewhat pessimistic. So, will go with broken MVFR clouds around
2.5kft for the evening hours.

Winds will be southeast at 10kts or less through the night and
tomorrow morning, but when the boundary moves through, winds will
become northerly and be breezy with gusts around 20kft for late
morning through afternoon at all sites. Wind speeds will decrease
during the evening hours.

Auten

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST early this morning for
ILZ027>031-036>038-040>048-053>057-063.

&&

$$