Normal, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

930
FXUS63 KILX 020433
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1033 PM CST Sun Feb 1 2026

.KEY MESSAGES...

- Light snow (60-80% chance) this afternoon and evening will
  result in slick spots on roadways. Allow extra time to reach
  your destination and take it slow on the way.

- There is a 20-30% chance for accumulating snow southeast of a
  Shelbyville to Paris line on Tuesday. Flurries may occur Monday
  night into Tuesday morning further north, but accumulations
  there should be minimal.

- Temperatures will be less cold this work week, with highs
  generally in the 20s and 30s Monday through Thursday.

&&

.UPDATE...
Issued at 717 PM CST Sun Feb 1 2026

Water vapor imagery this hour shows the defined curl associated
with the upper trough now centered just northwest of Bloomington.
Some heavier snow showers associated with this curl have been
tracking along the I-74 corridor, with a broader area of light
snow extending from Havana southeast to near Vandalia. Webcams and
traffic are not showing many impacts so far, with mainly a thin
coating of snow on surfaces that do not already have a heavy
concentration of residual snow/ice treatment. Evening sounding
from our office still shows a decent dry layer below 850 mb, which
appears to be keeping things in check.

Upstream, the surface boundary is pushing southeast across central
Iowa. Surface reports have been indicating some light freezing
drizzle in that area. HRRR forecast soundings do show we begin to
lose ice crystals in the column after 9-10 pm, so potential for
light icing this far south will need to be watched closely.

Geelhart

&&

.DISCUSSION...
Issued at 1255 PM CST Sun Feb 1 2026

***** LIGHT SNOW THIS EVENING *****

At 1pm Sunday, temperatures were in the upper teens to low 20s
across central and southeast IL. Surface high pressure was shifting
eastward into the Ohio Valley, allowing for south-southwest winds
across the region. Meanwhile, a shortwave trough was diving
southeast into the area to bring widespread clouds and an area of
light snow. Though taking time to erode the dry air in place (PWAT
on our 12z raob was 0.12"), snow should spread east of the IL River
to overtake most of central/southeast IL over the next few hours.
Accumulations will be light with this activity, with most locations
seeing between a dusting and an inch - enough to cause some slick
patches on roadways.

***** LESS COLD TOMORROW *****

After so many nights with lows in the single digits above/below 0,
cloud cover and lingering flurries tonight will limit radiational
losses favoring a milder night with lows in the upper teens. While
some of those clouds will hang on tomorrow (mainly east of I-55),
ridging quick to expand back into the area on the heels of today`s
shortwave trough will favor a warmer day with highs likely (60-80%
chance, per NBM and REFS) reaching the 30s - warmest in west-central
IL. This will be the first time many locations break 30 degrees
since January 22nd.

***** SNOW IN SOUTHEAST IL TUESDAY? *****

Another trough will flatten the ridge tomorrow evening into Tuesday,
with a surface low passing across the TN/OH Valleys on Tuesday.
While that will be the feature to watch for accumulating snow in
areas mainly south of a Shelbyville to Paris line on Tuesday, small
vort maxes further north could provide sufficient lift for a few
flurries across the rest of central IL as early as tomorrow night.
With the NAM/GFS suggesting a brief period of negative saturated EPV
atop a band of modest FGEN in the 650-500mb layer (indicative of
CSI), and time heights likewise showing a "crosshair" signature
(vertical motion max and RH > 90% in the DGZ) on Tuesday, we suspect
a quick 1-3 inches of snow will accumulate in a narrow band. The
question is where, and that remains to be seen. At this time, the
highest chances (20-40%) for seeing more than an inch of snow from
NBM/LREF are outside our area in southern IN/northern KY, though
areas south of I-70 in southeast IL still stand around a 20% chance.

***** SEASONABLE TEMPERATURES MID-LATE WEEK *****

Dry conditions should return Tuesday night as surface high pressure
settles back into the region. Depending on cloud cover, Tuesday and
especially Wednesday nights could feature some single digit lows,
with NBM giving the highest chances (50-70%) in eastern IL Wednesday
night. As the surface high shifts east, warm advection will return
on Thursday to usher milder temperatures back into the region,
though with southwest winds gusting to 30 mph it won`t exactly feel
warm. It remains unclear precisely when the shortwave trough and
attendant surface low will swing through the local area, and also
how far west the cold air spills, which is resulting in low
confidence in forecast temperatures Thursday night through Saturday.
The deterministic models and their respective ensembles have
generally trended further east with the push of arctic air, with the
LREF mean now confining sub -20 degC 850mb temps to Upstate NY. Our
area looks to receive a glancing blow, with temperatures moderating
as ridging expands back into the region early next week (of 2/8),
though it`s worth noting a subset (~20%) of LREF hold onto
near/below normal 500mb heights through Monday, 2/9. The highest
chance (40-60%) for high temperatures over 40 degF in this forecast
package (through Saturday, 2/7) is west of I-55 on Friday.

Bumgardner

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1033 PM CST Sun Feb 1 2026

MVFR conditions thus far have been more associated with passing
light snow, but a larger area of sub-3000 foot ceilings is
advancing southeast toward the Illinois River. All TAF sites
should have about a 4-6 hour period of MVFR ceilings, before a
surface boundary shifts winds to the northwest and clouds begin to
scatter out. KCMI may take much of the morning to see conditions
improve, as ensemble guidance keeps MVFR probabilities up to
50-70% as late as 17z.

Geelhart

&&

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

$$