Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

817
FXUS63 KDVN 241055
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
455 AM CST Sat Jan 24 2026

.KEY MESSAGES...

- Wind chill values in the -15 to -30 degree range will continue to
be felt this morning, as cold temperatures combine with winds of 5
to 10 mph. . A Cold Weather Advisory remains in effect until Noon
today.

- A Winter Weather Advisory continues for the far southern CWA. A
sharp cutoff of snow amounts is expected on the northern edge of
this system between Highway 34 and I-80.

- Below normal temperatures continue next week, with cold
  weather headlines possible Sunday night and Wednesday night.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 138 AM CST Sat Jan 24 2026

Despite widespread high cloud cover and a lack of widespread snow
cover, our overnight temperatures are remaining very cold, in the
-5s in far south to around -10 in the north 1/2 of the area. Winds
are continuing to be 5 to 10 mph, producing patchy wind chills as
cold as -30 in spots, but generally running in the -20s, thus the
advisory is the best suited product for this.

Temperatures today are forecast by nearly all guidance to rise into
the 0 to 8 range. While that seems pretty cold, and I`ll not adjust
it, I am concerned that we`re already cloudy, and the strength
of the shallow Arctic air may keep highs a bit cooler, with
possibly areas over snow on seeing zero to -3 for highs.

The high clouds overhead are the northern reach of the broad winter
storm well to our south. This high cloud cover will become more
dense today, and saturate slowly from top down. This process will
eventually lead to snow reaching the surface, mainly in the far
southern portion of the area. The dry low levels will inhibit this
process, but the depth of this dry air is shallow (arctic air
generally is). Looking aloft, the temp profile and moisture / lift
today and tonight are in the dendritic layer aloft, which is rather
deep, possibly 10kft deep.  That favors high ratio snow, but in
general, model QPF has gone down, and only 0.05 to 0.08 of total QPF
is now forecast in our south, resulting in snow amount forecasts
settling into the 1 to 3 inch range. Probs of 2 or more inches
remains high in the far south, in the 60-75% range, but amounts of 4
inches probs have dropped to a maximum of 40% around the Macomb
area, with much lower values to the north.  Thus, a 1-3 range, with
spotty 4 inch amounts seems to capture this event`s range.

In our far eastern CWA, snow tonight is forecast to be somewhat
lower end but in the 1-2 inch range, and that could linger into
Sunday morning there.

Pops today will gradually increase from low chance south to likely
south by afternoon, with 50-70% pops spreading north to around
Highway 30 and south this evening, then shifting east to be mainly
in Illinois after midnight and into Sunday morning.  These later
hours of snow chances are for extremely light amounts of snow as the
main system to the south moves towards the Ohio Valley.

In the wake of the departing southern system, another push of cold
Arctic air will rotate south over the region, Sunday night, with
lows back in the negative single digits south to near -10 in the
north, all combined with steady winds of 10 mph, gusting to 20 mph.
This combo is expected to bring wind chills of -15 to -27 to much of
the area, and a wind chill based cold weather advisory seems likely
to be needed Sunday night through Monday mid morning.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 138 AM CST Sat Jan 24 2026

The extended beyond Monday night remains consistently below normal,
as a messy northwest flow, or at the western portion of the deep
upper low in the Great Lakes.  Either way, and we`re cold, with some
passing threat for snow in waves in this flow/rotating around the
upper low.  The chances for snow at this point are low in any one
period as timing and position of any wave is inconsistent.  That all
said, cold air is in place, and snow should happen as some point.

Lows in the 5 to -5 range are forecast may of the nights ahead,
which could keep us near advisory range for wind chill driven
headlines.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 447 AM CST Sat Jan 24 2026

VFR conditions will prevail through much of the TAF period, with
conditions starting to deteriorate at BRL between 21-00z, as
light snow starts to work into the area. Confidence in the
northerly extent of snow is low at this point, but opted to
include MLI with a PROB30 group between 00-04z this evening.
As the snow moves in, we will largely see MVFR conditions, with
cigs between 1500-3000 ft and vis between 3-5 SM. We may see
some brief reductions in vis below 3 SM, especially at BRL.
Winds will remain light and northeasterly through much of the
TAF period.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Cold Weather Advisory until noon CST today for IAZ040>042-
     051>054-063>068-076>078-087>089-098-099.
IL...Cold Weather Advisory until noon CST today for ILZ001-002-007-
     009-015>018-024>026-034-035.
     Winter Weather Advisory from 3 PM this afternoon to 3 PM CST
     Sunday for ILZ034-035.
MO...Cold Weather Advisory until noon CST today for MOZ009-010.
     Winter Weather Advisory from 3 PM this afternoon to 3 PM CST
     Sunday for MOZ009-010.

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Gunkel