Normal, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

605
FXUS63 KILX 021916
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
116 PM CST Mon Feb 2 2026

.KEY MESSAGES...

 - Light snow is possible (20% chance) late tonight through Tuesday
   morning, primarily near the I-74 and I-70 corridors. Any
   accumulations will be very minor, with a 20 to 40% chance of a
   half-inch of snow east of I-57.

 - Mild temperatures return late this week. There is over 80%
   probability of temperatures rising above freezing west of I-55
   Thursday and over 90% probability across the entire Friday.

&&

.DISCUSSION...
Issued at 104 PM CST Mon Feb 2 2026

Quiet weather is expected for the remainder of today and tonight
as Central Illinois finds itself within a low-level col area, and
within general subsidence beneath an area of strong mid-level
height rises.

Our focus shifts late tonight into Tuesday morning as a shortwave
trough currently over the Dakotas causes a subtle buckle in the
mid-level ridge. A couple of regional models (NAM/GEM) are hinting
at a corridor of strong mid-level frontogenesis translating
southeast near/along the I-74 corridor. NAM forecast soundings,
however, reveal that the strongest forcing will initially be spent
on saturating the very dry low and mid-levels of the atmosphere,
with forcing weakening considerably by the time the column
supports snow reaching the surface. Given the inconsistencies
between the regional and global models and the concern over the
extremely dry antecedent airmass, we will maintain only low-end
PoPs (20%) north of I-74 tonight associated with this feature.

Further south, near the I-70 corridor, mid-level warm air
advection (WAA) will increase late tonight ahead of the
approaching shortwave, followed by peak positive differential
cyclonic vorticity advection (dCVA) during the Tuesday morning and
early afternoon hours. Similar concerns exist regarding the dry
air across the southeastern counties. However, forcing is expected
to persist a few hours longer once saturation is achieved, which
should allow for some very minor accumulations. The NBM
probability for 1 inch of snow is low (10-20%) east of I-57, with
a slightly higher 20 to 40 percent chance of at least a half-inch
of snow.

A broad 1030mb high pressure system centered over the northern
Great Plains and Upper Midwest Tuesday evening will slowly inch
toward and across Central Illinois Wednesday and Thursday. This
will keep the weather dry but initially colder, with highs only in
the 20s Wednesday. Overnight lows will drop into the single
digits or low teens Wednesday morning and Wednesday night.

Looking beyond midweek, a significant downsloping event is
forecast to develop lee of the northern Rockies, with 850mb
temperatures warming substantially to 10-15C across Alberta and
Montana. This much warmer airmass will translate southeast and
clip portions of Central Illinois starting Thursday into early
Friday ahead of an approaching cold front. Widespread temperatures
above the freezing mark are expected (NBM 80-95% probability)
west of I-55 Thursday, becoming areawide (NBM >90% probability)
early Friday before the front pushes through. The downsloping
effect will not only produce warmer temperatures but also an
extremely dry airmass, keeping the probability of any
precipitation with the frontal passage quite low (10%). Non-
diurnal temperature trends will be possible if the front moves
through early during the day Friday.

Deubelbeiss

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1151 AM CST Mon Feb 2 2026

MVFR ceilings prevail across central IL late Monday morning,
though periods of VFR have been observed at SPI and areas further
south where ceilings are higher and near the 3kft threshold. Added
a tempo group to each of the the I-72 airfields to account for
the potential category-crossing ceiling fluctuations over the next
several hours. HREF suggests medium-high confidence (80% chance)
these ceilings will break up by sunset, though additional lower
ceilings and even some flurries could sink into the region again
early Tuesday morning.

Bumgardner

&&

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

$$