996
FXUS63 KILX 071718
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1118 AM CST Sun Dec 7 2025

.KEY MESSAGES...

- 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 18z TAFs through 18z Monday Afternoon)
Issued at 1118 AM CST Sun Dec 7 2025

Low ceilings of 500 feet or less continue over much of central
Illinois late morning, but conditions have improved to MVFR near
KPIA and the Illinois River valley. While some clearing has taken
place upstream, it has begun to fill in once again. KPIA stands
the best chance of getting into VFR range this afternoon, while
the general trend will be for most improvement across central
Illinois to be during the evening. However, visibility should be
significantly improved by mid afternoon.

Gusty north winds will continue behind a cold front through the
afternoon, but winds become light and variable early Monday.

Geelhart

&&

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

$$