316
FXUS63 KILX 010340
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
940 PM CST Sun Nov 30 2025

.KEY MESSAGES...

- A fast-moving storm system will bring another round of snow to
  central Illinois from Monday afternoon through Monday night. The
  highest accumulations of 2 to 4 inches will occur along and
  north of a Beardstown to Bloomington line.

- Much below normal temperatures will prevail through next
  weekend...with the coldest readings arriving Thursday night when
  12z NBM guidance suggests a 40-60% chance of lows dipping below
  zero along and north of a Macomb to Tuscola line.

&&

.UPDATE...
Issued at 835 PM CST Sun Nov 30 2025

Added mention of freezing fog to the grids after midnight along
the I-72 corridor, primarily east of Springfield. Satellite
imagery shows clearing working southwest through Champaign and
Decatur. As winds go calm tonight and dewpoint depressions drop
near zero in areas that clear out, short range guidance shows
fog, some potentially dense, developing. Will monitor trends over
the next several hours, but cannot rule out the eventual need for
a focused Dense Fog Advisory. If dense fog does form, slick spots
will likely develop as we head into the morning commute.

25

&&

.SHORT TERM... (Tonight through Monday)
Issued at 142 PM CST Sun Nov 30 2025

Low clouds will continue to blanket central Illinois for the
balance of the afternoon through tonight: however, other than a
few snow flurries, no appreciable weather is expected. The lull in
wintery weather will be short-lived however, as a short-wave
trough evident on 19z/1pm water vapor imagery over the Great Basin
dives southeastward and leads to cyclogenesis across the Deep
South by Monday evening. While the actual surface low will track
well south of central Illinois, a band of strong frontogenesis
will develop across the region during the day Monday. Forcing
becomes most prevalent within the 800-700mb layer west of I-55
toward midday...then spreads E/SE across the remainder of the area
during the afternoon and evening. While forecast soundings
initially show a dry boundary layer, top-down moistening will lead
to the development of light snow across the Illinois River Valley
by midday...with the snow then spreading eastward to the Indiana
border by late afternoon. While deep-layer moisture will be
limited and the resulting QPF will be considerably lighter than
with the previous storm system, the colder/drier airmass will lead
to higher SLR`s of 12:1 to 15:1 during the precip event. As a
result, am expecting a general light snowfall across all of
central and southeast Illinois...with the highest amounts of 2 to
4 inches focused along/north of a Beardstown...to Lincoln...to
Bloomington line. Further south, 1 to 2 inches will be common.
While motorists will have dry conditions for the Monday morning
commute, snow-covered roads will be in store for the evening
commute...especially along/west of the I-57 corridor. The light
snow will taper off and come to an end from west to east Monday
night.


Barnes

.LONG TERM... (Tuesday through Next Sunday)
Issued at 142 PM CST Sun Nov 30 2025

Cold and dry weather with highs in the middle to upper 20s is
anticipated for Tuesday before winds become S/SW ahead of the next
approaching cold front and a brief warming trend into the middle
30s occurs on Wednesday. A few models are suggesting the cold
front may be accompanied by a few snow-showers late Wednesday
afternoon into Wednesday night: however, the dry boundary layer
will prevent any appreciable precip. Once the front passes, strong
CAA will spill into the region for Thursday...resulting in high
temperatures struggling to reach 20 degrees everywhere north of
I-70. As skies clear and winds diminish, bitterly cold conditions
are expected Thursday night. 12z NBM guidance suggests a 40-60%
chance of sub-zero lows along/north of a Macomb to Tuscola line.
After that, yet another southern-stream storm system will spread
moisture back into Illinois on Friday. The atmosphere will
initially be cold enough to support all snow: however, as an
elevated warm layer advects northward, there could potentially be
some light freezing rain along/south of I-70 Friday night. It is
still too early to pinpoint any specific snow/ice accumulations at
this time. While the system will not be as strong as the one that
impacted central Illinois yesterday, it has the potential to bring
another light snow accumulation by the end of the week. Once this
wave passes, cold and generally dry weather is expected next
weekend.

Barnes

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 940 PM CST Sun Nov 30 2025

A large hole has opened in the MVFR ceilings from KDEC-KCMI.
Unsure how far west this clearing will extend overnight. Areas
that due clear out stand a good chance to see IFR cig/vis
develop, and have added this either as predominant or tempo
conditions at all terminals except KPIA through 13-14z. Main
forecast issue for Monday is an approaching storm system that will
spread accumulating snow over the terminals during the afternoon.
IFR conditions are likely for several hours with snow starting to
taper off toward the end of this TAF period.

25

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from noon Monday to 6 AM CST Tuesday for
ILZ027>031-036>038-040>043-047-048.

&&

$$