628
FXUS63 KILX 091801
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1201 PM CST Tue Dec 9 2025

.KEY MESSAGES...

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

- A clipper system will bring a round of light snow by Thursday
  night into Friday morning...with the 00z LREF suggesting a
  40-60% chance of greater than 1 inch of snow along and north 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.

&&

.SHORT TERM... (Today through Wednesday)
Issued at 332 AM CST Tue Dec 9 2025

As the pressure gradient tightens between a sprawling ridge over
the E/SE CONUS and an approaching Alberta clipper, S/SW winds will
increase and bring much milder air into central Illinois today.
Despite the lingering snow cover, strong WAA and partial sunshine
will result in afternoon high temperatures in the upper 30s and
lower 40s...with warmer readings in the middle 40s along/south of
a Jacksonville to Effingham line. SW winds will continue to
increase tonight, with numeric guidance and HRRR/RAP output
indicating widespread gusts of 30-35mph from late evening through
the overnight hours. Given the continued WAA, temperatures will
slowly rise after dark...reaching the lower to middle 40s across
the board by midnight. Meanwhile a band of rain showers will skirt
through central Illinois as the main surface low passes well to
the north across southern Wisconsin. The showers will be most
numerous along/north of I-72 where 60-80 PoPs are warranted and
will quickly push into Indiana before dawn Wednesday.

As the low tracks further east, it will pull a cold front through
the area Wednesday morning. 00z Dec 9 CAMs are showing a band of
convective rain/snow-showers immediately behind the front. Given
the tight pressure gradient and very strong winds aloft, the
NAM/HRRR are suggesting NW wind gusts with the showers will
likely reach 40-50mph. Motorists may need to keep an eye on the
radar if traveling Wednesday morning, as the snow-showers will
have the potential to significantly cut visibility for a time as
they quickly traverse the area. The most significant showers will
depart the KILX CWA by midday, with only a few lighter showers
during the afternoon into the evening. Morning high temperatures
will range from the middle 30s northwest of the Illinois River
around Galesburg to the middle 40s south of I-70...with readings
dropping into the lower to middle 30s everywhere by mid to late
afternoon.

Barnes

.LONG TERM... (Thursday through Monday)
Issued at 332 AM CST Tue Dec 9 2025

Models continue to struggle with the next in a series of clipper
systems slated to impact parts of the region late this week into
the weekend. The 00z Dec 9 suite is beginning to hone in on the
Thursday night into Friday morning time frame: however, the exact
track is still in question. Have therefore kept PoPs quite low
(20%) during the day Thursday, but have increased them into the
30-50% range for Thursday night. While the system will not have a
lot of moisture to work with, a light accumulation of snow is
likely. The 00z LREF shows a 40-60% chance of greater than 1 inch
along/northeast of a Macomb...to Springfield...to Robinson
line...with just a 10% chance of over 3 inches along/north of
I-74.

A second clipper will come into the picture by Saturday...with
most guidance suggesting the highest probability of accumulating
snow across Iowa into northern Illinois. Once this system exits, a
bitterly cold airmass will settle into the Midwest through early
next week. High temperatures will drop from the 30s on Friday into
the teens for Saturday and Sunday. While wind-chill values will
drop 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
along/north of I-72. 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 18z TAFs through 18z Wednesday Afternoon)
Issued at 1200 AM CST Tue Dec 9 2025

A strong low pressure system in the Dakotas will track southeast
across southern Minnesota, Wisconsin, and into southwest Lower
Michigan tonight, bringing active weather to central Illinois.
Conditions will remain VFR through most or all of the overnight
period, though scattered showers may impact the terminals this
evening (highest chances at PIA, BMI, and CMI). Southwest winds
will gust sporadically over 25 kt this evening into the overnight
period, but when they will become much stronger when they switch
over to a west-northwesterly direction between 09 and 12z;
frequent 30-40 kt gusts are expected, with localized gusts to 50
kt with any snow showers that form along the secondary cold front
during the 10-15z time frame. Those winds will veer to a north-
northwesterly direction and gradually ease after roughly 16-17z,
but MVFR ceilings (arriving with the cold front between 09 and
12z) should persist through the afternoon.

Bumgardner

&&

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

$$