729
FXUS63 KILX 082308
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
508 PM CST Mon Dec 8 2025

.KEY MESSAGES...

- Windy conditions are expected Tuesday night and Wednesday, with
  some gusts over 40 mph. Travel difficulties will be most noted
  on west-east roadways Tuesday night, then on north-south roads
  on Wednesday.

- While much of the precipitation with this system will be rain,
  Wednesday will have the potential for a few snow squalls, which
  would rapidly decrease visibility for short periods of time.

- Light snow will accompany another clipper system late this week,
  with about a 30-40% chance of seeing over an inch of snow near
  and north of I-74.

- Another surge of Arctic air is incoming for the weekend, with
  widespread wind chills below zero and temperatures about 25-30
  degrees below normal.

&&

.SHORT TERM...  (Through Wednesday)
Issued at 200 PM CST Mon Dec 8 2025

Fairly quiet across the forecast area today, aside from a band of
clouds slowly edging east of the Illinois River. Warmest
conditions are south of I-70 where the snow cover has eroded, and
temperatures are largely in the lower 30s. 20s prevail elsewhere.

Water vapor imagery shows the next shortwave beginning to drop
into North Dakota, and this should be in the vicinity of Lake
Michigan by morning. Low temperatures will occur in the evening,
as a developing low level jet will push temperatures upward
overnight. With high temperatures Tuesday reaching the low-mid 40s
and temperatures remaining above freezing Tuesday night, the
strengthening clipper system looks to be more of a rain event for
our area initially. However, cyclonic circulation behind this
system and falling temperatures on Wednesday will support some
scattered snow showers. Will need to keep an eye on potential for
some snow squalls, with some rather steep 3-hour pressure rises
and surface based CAPE`s up to 100 J/kg.

The other item of concern will be with the winds Tuesday night into
Wednesday. A tightening pressure gradient is expected Tuesday
night as the surface low moves to Lake Michigan. HREF guidance
brings probabilities of 40+ mph wind gusts up to 75% by midnight,
with pockets of 40-50% probabilities of over 50 mph. Some of the
high-res guidance is suggesting widespread wind gusts 50-55 mph.
While NAM soundings are showing 50-60 knot winds a few thousand
feet off the surface, the lingering inversion would suggest not
all of that would mix down. Some of the NBM 75th percentile wind
speeds and gusts were blended into the initialization to bump up
the winds, but not enough to require wind headlines yet.

Geelhart

.LONG TERM...  (Thursday through Next Monday)
Issued at 200 PM CST Mon Dec 8 2025

Latest ensemble guidance has been trending more toward Thursday
night into early Friday morning with the next clipper system,
with the European guidance on the stronger side. NBM guidance
shows about a 30-40% chance of more than 1 inch of snow near and
north of I-74, fairly close to last night`s LREF guidance.
Deterministic guidance is also rather bullish on another area of
light snow streaking eastward across the area on Saturday, with a
handful of ensembles supporting it, though run-to-run consistency
isn`t in place yet.

Big question in the extended range will be with the next Arctic
surge. NBM guidance continues to advertise temperatures a good
25-30 degrees below normal for the weekend, with lows mainly in
the single digits and highs in the teens to lower 20s over most
areas. Earlier guidance had been more supportive of a widespread
wind chill below -15F (local cold weather advisory criteria),
though the latest NBM is more in the -5 to -10 range. If we do get
a decent amount of snow from the Thursday system, the fresh snow
cover would help get temperatures down low enough to compensate.
Wind chills by Sunday night would ease up as high pressure settles
into the area.

Geelhart

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 508 PM CST Mon Dec 8 2025

VFR skies are forecast to dominate most central IL terminals this
TAF cycle. The exception is KPIA-KBMI, where we have medium to
high confidence that an area of MVFR ceilings currently over
northeast IA will drop southeast, moving into those sites around
sunrise. Poor agreement among short range guidance on how long
these ceilings will persist, so went more pessimistic/slower with
clearing given trends we often see during the cool season. Light
winds this evening will increase overnight as high pressure shifts
east of the region. South to southwest winds will gust near 20 kt
at times into Tuesday afternoon.


25

&&

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

$$