Evanston, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

932
FXUS63 KLOT 241148
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
548 AM CST Sat Jan 24 2026

.KEY MESSAGES...

- Bitterly cold conditions will persist through this morning.

- Another period of very cold conditions will occur early
  Monday morning with wind chills or 15 to 25 below.

- Fluffy accumulating snow paired with cold temperatures will
  lead to hazardous travel conditions in many locations from
  this evening through much of the day Sunday. The highest
  snowfall accumulations and greatest travel impacts are
  expected near and east of Interstate 55 and near/along the
  Illinois lakeshore.

&&

.DISCUSSION...
Issued at 327 AM CST Sat Jan 24 2026

Through Sunday Night:

It`s another frigid morning out there as the well-advertised
Arctic air mass continues to make its presence known. Air
temperatures at press time are below zero across the area with
wind chills generally between -20 and -30F, coldest across our
northern counties. These readings will not change much until
after sunrise, and even then, a relatively thick cirrus canopy
will hamper warming efforts to some degree, keeping today`s high
temperatures in the single digits to at or slightly above 10F.
Did opt to extend the going Cold Weather Advisory until noon to
better align that with the advisory expiration times of our
neighboring WFOs, but the overall message of another frigid
morning has not changed, so bundle up in multiple layers if you
need to go outside!

Also ongoing this morning is a stubborn ribbon of lake effect
snow in northwest Indiana. Will continue to message the
likelihood of resultant slick travel conditions in northern
Porter County (and possibly northern Lake County, IN later on)
with Special Weather Statements. Eventually, the lake effect
snow band will retreat offshore and back over Lake Michigan
later this morning as near-surface flow on the band`s eastern
flank veers from an easterly to a southerly direction with time.

This weekend`s weather headline-maker is the absolute unit of a
winter storm that will produce significant wintry impacts
across a large swath of the central and eastern CONUS, including
portions of the Deep South. The storm`s massive size can be
attributed to the Arctic air mass clashing with a substantial
poleward influx of Gulf and sub-tropical Pacific moisture. This
has yielded an expansive swath of precipitation across the
southern central CONUS this morning, which is only expected to
grow in size today into Sunday as a strengthening sub-tropical
jet continues to funnel moisture into the CONUS while a cut-off
upper low off the coast of Baja California begins to eject
northeastward while undergoing a complex phasing process with
two northern stream troughs. Aided by broad upper-level
divergence in the right entrance region of a westerly polar jet
streak, this storm`s precipitation will spread into our
forecast area from southwest to northeast in the form of snow by
as early as this afternoon. System snow will then likely
continue across at least a portion of our forecast area all the
way through late Sunday afternoon/evening. Lake enhancement will
also likely start to occur Saturday night/Sunday morning, before
transitioning to a more bona fide lake effect snow and
lingering beyond the end time of the system snow until closer to
midnight.

One lingering point of forecast uncertainty remains how far
northwest the steadier snowfall will be able to spread with a
strong Arctic high to our northwest supplying a feed of dry air
into the area. While our northwestern counties could still see a
period of light snowfall this evening, the steadier snowfall
will remain focused in the southeastern half of our CWA (and
within any lake effect snow bands) thereafter as the drier air
attempts to gradually creep eastward. A sharp snowfall gradient
will likely occur across our forecast area as a result -- one
that will likely be tighter than what can reasonably be depicted
in our gridded forecast database.

Wherever the steadier snowfall does end up occurring, an
exceptionally deep dendritic growth zone and the aforementioned
cold air temperatures will yield a dry, powdery type of snow
with snow-to-liquid ratios favored to average out around or
just above 20:1. With the more pronounced mesoscale forcing
mechanisms remaining displaced to our south, snowfall rates
aren`t expected to be exceptional -- generally remaining at or
below 0.5"/hour. Briefly higher rates closer to 1"/hour aren`t
out of the question, though, in the more robust lake effect
banding and in our far southeastern counties during the height
of the synoptic snowfall late Saturday night/Sunday morning as
an increasingly coupled jet structure strengthens broad-scale
ascent. However, even without eye-popping snowfall rates, the
prolonged duration of the snowfall will still allow for anywhere
from a few to several inches of snow accumulation to be
observed wherever the steadier snowfall has some staying power.

Have hoisted a Winter Weather Advisory for roughly the
southeastern half of our forecast area (plus Lake County, IL),
where confidence is highest in multiple inches of snow
accumulation occurring and hazardous travel conditions
materializing as a consequence of the cold air temperatures
making it easier for snow to accumulate on roadways. It is
possible that some locations could end up seeing snowfall totals
of 6" or greater, and did give consideration to a Winter Storm
Warning for a portion of our southeastern CWA for that reason.
However, with our presently forecasted snowfall amounts being
borderline for a Winter Storm Warning issuance and most other
headline decision factors (long snowfall duration, less-than-
stellar snowfall rates, winds not expected to be particularly
strong, etc.) pointing towards the issuance of an advisory over
a warning, elected to go with an advisory headline. Did segment
the advisory product accordingly to account for where snowfall
totals may be higher relative to other areas. That said, if
confidence increases in solidly 6+" snowfall totals being
observed somewhere, then an upgrade to a Winter Storm Warning
may eventually be warranted for those locations.

Ogorek


Monday through Friday:

Following the weekend system, an energetic and active upper
pattern will remain in place with fast, northwesterly flow
aloft likely to guide additional disturbances across the Upper
Midwest and Great Lakes region through the week. Regarding late
Sunday night/Monday morning: latest guidance suggest we may need
some additional cold weather headlines during this period to
start the week with wind chills in the 15 to 25 below range.

Latest indications point to generally precip-free conditions on
Monday as fairly robust mid-level height rises spread in from
the west through the afternoon. The nose of a ~130 kt jet
streak will impinge on the region late in the day, but at this
time only looks like it`ll drag some increasing mid and high-
level cloud cover overhead. Northwest to west-southwest breezes
with a lingering fairly tight surface pressure gradient will
hold wind chills largely below zero through the day.

On Monday night, a fast-moving and fairly robust disturbance is
slated to press southward out of the Minnesota Arrowhead Region
and across the Great Lakes. Latest guidance currently takes the
bulk of the most intense large scale forcing with this system
to our north, and will continue with a dry forecast in our area
as a result. The associated surface low will eventually drag a
reinforcing cold front through the area on Tuesday which will
send air temperatures back down to around 0 degrees Tuesday
night with colder wind chills. In the wake of the front,
forecast soundings look a bit more supportive of some
intermittent flurries as lobes of strong shear vorticity meander
southward through the afternoon and evening with increased
saturation in a thin layer at the base of a deep DGZ. Good
agreement that the boundary layer flow will remain westerly
enough to keep an follow-up LES to our east.

Another, potentially even more intense shortwave is forecast to
drop more solidly across our area on Wednesday and Wednesday
night. Guidance generally appears supportive of a period of
light snow somewhere in the vicinity, although noting a fair
amount of north- south spread in the current deterministic and
ensemble output. At this point, didn`t see any reason to stray
from the NBM-delivered chance PoPs during this period. Where
snow does fall, very cold temperatures in the single digits and
teens will once again lead to travel impacts.

Beyond this time, forecast confidence breaks down a bit, but
there`s an interesting signal of a fast-moving vort lobe
backing southwest across lower Michigan sometime during the late
Wednesday night - Thursday timeframe. This could potentially
restart the LES potential in our area, but confidence is pretty
low in specifics at this time.

Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 548 AM CST Sat Jan 24 2026

Ongoing lake effect snow band just east of the GYY 10 mile ring
will continue to shift west early this morning. Expectation is
for the main axis of snow to begin pivoting northward a bit and
may take the lowest vsbys north/northeast of the terminal, but
given how close things are, elected to introduce a brief TEMPO
in the 13-15z window for snow.

Elsewhere, VFR conditions are expected today with easing
northwesterly winds eventually turning northeast to easterly
this afternoon and evening. Light snow is expected to overspread
the region late this afternoon, but more so this evening and
overnight. No changes to the inherited PROB30 groups for IFR -SN
at the front end, with the prevailing lines looking good timing
wise to drop to IFR during the mid-late evening. At ORD/MDW,
lake enhancement may support lower cigs/vsbys (possibly LIFR) towards
Sunday morning, but not confident enough in this to justify
TEMPO groups at this range. Uncertainty in wind trends also
exists, mainly after about 10-12z Sunday when convergence
associated with lake enhancement may result in winds turning NW
at ORD and NNW to E at times at MDW.

RFD will sit at the northwestern edge of the main area of snow.
As a result, uncertainty in snow timing and specific vsbys
remains. Trend at this point is towards a period of IFR to low-
MVFR vsbys in light snow overnight, but at this point elected to
continue a PROB30 given lingering uncertainties.

Carlaw

&&

.HYDROLOGY...
Issued at 230 PM CST Fri Jan 23 2026

River gauges, reports from local officials, and reports from
trained ice spotters continue to indicate a few ice jams across
the area due to the significant increase in river ice over
recent days. With continued cold weather into next week,
conditions will remain favorable for river ice formation. While
no widespread flooding is expected, localized ice jams may
occur.

- NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Cold Weather Advisory until noon CST today for ILZ003-ILZ004-
     ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-
     ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-ILZ104-
     ILZ105-ILZ106-ILZ107-ILZ108.

     Winter Weather Advisory from 6 PM this evening to 6 PM CST
     Sunday for ILZ006-ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-
     ILZ032-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

     Winter Weather Advisory from 6 PM this evening to 9 PM CST
     Sunday for ILZ033-ILZ039.

IN...Cold Weather Advisory until noon CST /1 PM EST/ today for
     INZ001-INZ002-INZ010-INZ011-INZ019.

     Winter Weather Advisory from 6 PM CST /7 PM EST/ this evening
     to 9 PM CST /10 PM EST/ Sunday for INZ010-INZ011-INZ019.

     Winter Weather Advisory from 6 PM this evening to midnight CST
     Sunday night for INZ001-INZ002.

LM...None.

&&

$$

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