NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 181021
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
421 AM CST Sun Jan 18 2026

.KEY MESSAGES...

- A Cold Weather Advisory is in effect late tonight through
  Monday morning across all of southern Wisconsin. Bitter cold
  wind chills of 23 to 29 below zero are expected during this
  period. Wind chills in the teens below zero are expected
  Monday afternoon into Tuesday morning.

- Light accumulating snow is expected this afternoon and
  evening, with new accumulations around 1 to 2 inches across
  the area. Gusty northwest winds later tonight into Monday may
  lead to some areas of blowing and drifting snow. Watch for
  slick spots and pockets of reduced visibility.

- A Gale Warning is in effect for all of Lake Michigan later
  tonight through Monday afternoon. A Heavy Freezing Spray
  Warning is in effect as well later tonight through Tuesday
  morning.

&&

.SHORT TERM...
Issued 421 AM CST Sun Jan 18 2026

Today through Monday night:

There is still some pesky flurry activity lingering in eastern
parts of the area early this morning, as one last area of weak
differential CVA pushes through with moist low levels in the
dendrite snow growth zone. This activity should push off to the
east by sunrise. There may be some pockets of clearing at times
into this morning, before more clouds move in by midday as warm
air advection develops.

Models are still in good agreement with a period of light snow
moving east southeast through southern Wisconsin this afternoon
into this evening, exiting to the east/northeast later tonight.
This is being driven by a passing Arctic cold front this
evening, with some low level frontogenesis response ahead of and
behind it and some differential CVA from a shortwave trough
passing just south of the area. Forecast soundings are saturated
in a deep layer with the dendrite snow growth zone tapped in the
low levels.

Look for the snow to move east into the area by middle
afternoon, peaking late afternoon and early evening, then
gradually exiting from west to east late evening into the
overnight hours. Snowfall rates should be up to one quarter
inch per hour, so a steady, light snow is expected. Snow to
liquid ratios will be around 20 to 1 or so, with one to two
inches of fluffy accumulation expected.

Strong cold air advection on gusty northwest winds are expected
after the Arctic cold front moves through. This may cause some
blowing and drifting snow, given the fluffy nature of the new
snow, as well as recent snowfall that probably has not
compacted much. Some visibility reductions may occur, as well as
some drifting on north to south roads. Will need to monitor if
this will be a more widespread issue in later forecasts.

The cold air advection will bring much colder temperatures and
wind chills into the area later tonight into Monday night. Lows
should drop into the single digits below zero over most of the
area, with wind chills in the 23 to 29 below zero range late
tonight into Monday morning. A Cold Weather Advisory is in
effect for the entire area during this period. Fairly confident
wind chills will not drop to the 30 below zero or colder
thresholds at this time.

Wind chills should remain in the teens below zero Monday
afternoon into Tuesday morning, with gusty west northwest winds
and temperatures in the single digits above zero Monday
afternoon, with lows Monday night in the single digits below
zero.

Wood

&&

.LONG TERM...
Issued 421 AM CST Sun Jan 18 2026

Tuesday through Saturday:

Synopsis: Mean upper troughing will continue to linger from the
Hudson Bay into the western Great Lakes through the duration of
the long term period. Given the persistent synoptic pattern,
southern Wisconsin will remain favorably positioned for impacts
from clipper systems, with attendant surface cold frontal
passages bringing additional bouts of very cold temperatures and
wind chills.

Tuesday evening into Wednesday is currently favored for the
most widespread snow potential across the area, with some signal
for accumulation in probabilistic forecast guidance. Low level
winds will turn northwesterly behind the Tuesday evening and
Wednesday system, with chilly temperatures and wind chills
settling in for the Wednesday night through Thursday time frame.

Signals for another clipper system are evident during the
Friday to Saturday time period, though high uncertainty remains
regarding wintry precipitation potential in southern Wisconsin.
Of greater confidence, however, is that another pull of Arctic
air will sag into the western Great Lakes with the affiliated
clipper system during the Friday-Saturday time period.
Additional very chilly temperatures and wind chills are thus
anticipated from the end of the upcoming work week into next
weekend.

Tuesday Night through Wednesday: Expect the next best chances
for widespread snowfall during this time frame. Snow will
initially focus along bands of 1000-700 mb frontogenesis & warm
advection Tuesday night through early Wednesday, with activity
trending more scattered in nature into Wednesday afternoon as a
cold front moves east of the area and cold advection becomes
predominant. Probabilistic forecasts from global ensemble
guidance and the NBM indicate some potential for accumulation,
though confidence in probabilities at any given location are
low, due to lingering north-south dispersion regarding system
track between ensemble members. Will continue to monitor trends
and offer additional details as track trends clarify in coming
forecasts.

Wednesday Night through Thursday: Expect another round of
chilly temps and wind chills as Arctic air re-establishes over
the western Great Lakes. Have maintained temperature and wind
chill forecasts from the NBM, which would keep conditions a
touch milder than Cold Weather Advisory criteria. Any colder
shifts, however, would push wind chills toward headline
thresholds during the Wednesday night through Thursday morning
period. Will thus be closely monitoring trends over coming
forecasts.

Thursday Night through Saturday: Guidance suggests that another
disturbance will cross the region, with possible phasing
between multiple areas of upper forcing making precipitation
chances more uncertain relative to Tuesday night into Wednesday.
Regardless of whether/not precip occurs, there is a much
stronger signal for another surge of Arctic air to make it into
the area along/behind the passing system. If current forecasts
from the NBM verify, this next Arctic surge could be even colder
than the one expected during the Wednesday night-Thursday
period. Will thus be monitoring for possible cold weather
headlines as this part of the period pulls closer.

Quigley

&&

.AVIATION...
Issued 421 AM CST Sun Jan 18 2026

There is still some pesky flurry activity lingering in eastern
parts of the area early this morning. This activity should push
off to the east by sunrise. There may be some pockets of
clearing at times into this morning, as well as ceilings varying
between 1500 and 4000 feet AGL, before more widespread ceilings
around or below 2500 feet AGL move in by early this afternoon.
Southwest winds are expected to remain gusty into midday, before
weakening somewhat this afternoon.

Models are still in good agreement with a period of light snow
moving east southeast through southern Wisconsin this afternoon
into this evening, exiting to the east/northeast later tonight.
This is being driven by a passing Arctic cold front this
evening.

Look for the snow to move east into the area by middle
afternoon, peaking late afternoon and early evening, then
gradually exiting from west to east late evening into the
overnight hours. Snowfall rates should be up to one quarter inch
per hour, so a steady, light snow is expected. One to two
inches of fluffy accumulation is expected. Ceilings should be in
the 1500 to 2500 foot AGL range, with visibility of 1 to 2
miles in the light snow.

Gusty northwest winds are expected by later tonight, after the
Arctic cold front moves through. This may cause some blowing and
drifting snow, given the fluffy nature of the new snow, as well
as recent snowfall that probably has not compacted much. Some
visibility reductions may occur, as well as some drifting on
north to south runways.

Wood

&&

.MARINE...
Issued 421 AM CST Sun Jan 18 2026

Low pressure around 29.8 inches will move from northwest
Minnesota this morning to the eastern Upper Peninsula of
Michigan today. West to southwest winds are expected today
across Lake Michigan.

The low will then strengthen to around 29.5 inches as is shifts
into eastern Ontario tonight, and into Quebec on Monday. An
Arctic cold front will move across the lake later this evening,
with northwest gales and heavy freezing spray expected behind
the front later tonight through Monday afternoon.

A Gale Warning is in effect for all of Lake Michigan later
tonight through Monday afternoon. A Gale Warning is in effect
for the nearshore waters of Lake Michigan later tonight through
Monday morning. A Small Craft Advisory will be needed Monday
afternoon and evening for lingering gusty northwest winds.

The strong winds will combine with building waves and cold
temperatures to bring heavy freezing spray later tonight through
Tuesday morning. A Heavy Freezing Spray Warning is in effect
during this period across all of Lake Michigan. Some freezing
spray is possible in the nearshore waters, mainly toward the
open waters.

High pressure around 30.5 inches will shift from the northern
Plains into the Lower Mississippi River Valley Tuesday, with
winds across Lake Michigan shifting west to southwest.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Cold Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
     WIZ057-WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-
     WIZ066-WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...3 AM
     Monday to noon Monday.

LM...Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...midnight
     Monday to 6 PM Monday.

     Heavy Freezing Spray Warning...LMZ080-LMZ261-LMZ362-LMZ364-
     LMZ366-LMZ563-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-
     LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...midnight Monday to noon Tuesday.

     Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646...midnight Monday
     to noon Monday.

&&

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee