915
FXUS63 KILX 021033
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
433 AM CST Tue Dec 2 2025

.KEY MESSAGES...

- Slippery morning commute possible due to yesterday`s snow and
  some patchy freezing fog.

- There is medium confidence (30-50%) in additional snowfall by
  Wednesday evening in areas north of Interstate 72. Our base
  case is between a dusting and one inch.

- The coldest air of the season will settle in Wednesday and
  Thursday nights. Wind chill values will approach advisory
  criteria up near Interstate 74.

- A clipper system will push across the Corn Belt this weekend.
  There is currently a low (20-25%) chance that snowfall will
  exceed 1 inch.

&&

.DISCUSSION...
Issued at 329 AM CST Tue Dec 2 2025

A compact shortwave trough is currently lifting north through the
lower Ohio River Valley this morning, as indicated by mid-level
water vapor imagery. A drier, subsident air mass is settling in
behind this feature. Regional model soundings show a shallow pinch
of moisture trapped beneath a strong subsidence inversion, which
is causing low stratus and pockets of dense fog. The combination
of yesterdays snow accumulation and todays patchy freezing fog may
result in a continued slippery morning commute.

Afternoon temperatures are expected to remain close to morning
lows, as light winds beneath the stubborn subsidence inversion
limit mixing and keep skies mostly cloudy. Low clouds will persist
into this evening, with temperatures falling into the mid-teens
to around 20 degF across the region.

Overnight, a good surge of warm air advection is expected as
surface winds shift southerly behind departing surface high
pressure. This will cause temperatures to slowly climb into the
low-to-mid 30s Wednesday afternoon ahead of an approaching cold
front.

There remains a decent signal for scattered snow showers to
develop behind the front by early Wednesday afternoon. This is
associated with a sharpening band of shallow FGEN (925-850 mb)
beneath a pair of phasing jet streaks aloft. The latest 00z RRFS
guidance suggests a medium chance (30-50%) for PoPs north of I-72,
with the wet-bulb temperature cold enough to support snow. This
same guidance also supports a range of QPF from a trace to 0.10
inches. Consequently, our base case forecast is for a dusting to
one inch of new snow accumulation in areas north of I-72.

The region will experience the coldest air of the season so far
from Wednesday night through Friday morning. Overnight lows will
drop into the single digits, and daytime highs will only reach the
teens, particularly in areas north of I-70. These conditions are
exceptionally cold for early December, running approximately 25-30
degrees below average. Furthermore, wind chill values in our
northern areas are expected to approach advisory criteria.

Marginally warmer and continued dry weather will then stretch
through late week as the storm system for Friday that we were once
concerned about passes well to our south. Nevertheless, there is
an emerging signal for another shot of light accumulating snow
this weekend as choppy northwest flow brings a clipper-like system
across the Corn Belt. Latest guidance from the NBM and Grand
Ensemble (GEFS, GEPS and EPS) support a 1 in 4 chance for at least
1 inch, though this probability may be artificially low due to
some timing differences that still exist.

MJA

&&

.AVIATION...  (For the 12z TAFs through 12z Wednesday Morning)
Issued at 426 AM CST Tue Dec 2 2025

Low-level stratus remains trapped beneath a strong subsidence
inversion, causing mostly IFR conditions across the regional
terminals early this morning. Model soundings mostly suggest that
this stratus remains intact through at least early afternoon as
light winds limit mixing beneath the inversion. Guidance supports
an improvement to VFR conditions at KPIA/KSPI/KDEC between
02z-05z, and then at KBMI/KCMI by 05z-08z, as surface winds shift
south and increase.

MJA

&&

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

$$