144
FXUS63 KMKX 191536 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
936 AM CST Sun Jan 19 2025

.KEY MESSAGES...

- A prolonged period of bitter cold air temperatures and wind
  chills continues through Tuesday. Cold Weather Advisories are
  in effect through Tuesday morning across all of southern
  Wisconsin.

- Heavy freezing spray continues through Tuesday afternoon over
  the southern half of Lake Michigan.

- Slight chances for light snow on Wednesday ahead of an
  approaching disturbance.

- Temperatures gradually trend back toward normal through middle
  to late in the week.

&&

.UPDATE...
Issued 936 AM CST Sun Jan 19 2025

Forecast appears largely on track with the cold weather
headlines into Tuesday morning. One change that may eventually
occur would be to consider an Extreme Cold Warning for the far
northern tier of counties for later Monday night into Tuesday
morning, as wind chills in those areas may drop to 30 below zero
or a little colder during that period. Also, the Cold Weather
Advisory may need to eventually be extended into Tuesday night
or Wednesday morning across most of the area, as wind chills are
close to 20 below zero at times.

Wood

&&

.SHORT TERM...
Issued 451 AM CST Sun Jan 19 2025

Today Through Tuesday Night:

Synopsis/Mesoanalysis: Cold air advection continues through this
afternoon/evening over southern Wisconsin, allowing Arctic air to
continue filtering into the region from Canada. Currently positioned
over Alaska, a shortwave ridge will drive southeast into west-
central Canada on Monday, allowing an area of surface high pressure
currently centered over the Northwest Territories to pivot into the
northern Rocky Mountains. Said high will continue to drift southeast
into the central Rockies during the day on Tuesday. The progression
of the aforementioned surface high will allow an even colder batch
of Arctic air to funnel into the western Great Lakes Monday night
into Tuesday morning, supporting the most frigid conditions of the
ongoing Arctic outbreak. Frigid air temps and wind chills will
continue Tuesday Night, though readings won`t be as cold as those
occurring earlier in the short term period. Be sure to dress warmly
if heading outdoors today through Tuesday Night.

Today & Tonight: Expect a frigid start to the day, with all
locations waking up to wind chills near/below -10 and air temps
near/below zero. The coldest of air temperatures and wind chills
will be outside of far southeastern Wisconsin, where a Cold Weather
Advisory is now in effect. Do expect that many locations will rise
above technical Cold Weather Advisory thresholds for a brief period
during the afternoon hours, with wind chills quickly tumbling back
to/below -20 after sunset this evening. It will be at this point
that widespread -20 or colder wind chills will overspread far
southeastern Wisconsin. In coordination with neighboring offices,
have thus bumped the start time of the Cold Weather Advisory for
Milwaukee, Racine, and Kenosha Cos up to 6 PM CST in the overnight
update.

Monday: Temps and wind chills will play out in largely similar
fashion to today, with wind chills briefly rising above -
20/technical Cold Weather Advisory thresholds during the afternoon
hours outside of central Wisconsin. Said wind chill rises will once
again be short-lived, with readings quickly plummeting following
sunset. Can`t rule out a few flurries near the Lake Michigan
shoreline, with no impacts anticipated in any activity.

Monday Night & Tuesday Morning: An renewed surge of Arctic air will
move into southern Wisconsin, supporting the coldest air
temperatures and wind chills of the ongoing Arctic outbreak. Expect
air temperatures to fall to or below -10 by early Tuesday morning in
most locations away from the immediate Lake Michigan shoreline. The
bitterly cold air temperatures will be accompanied by widespread
wind chills in the -20 to -30 range areawide, with even colder
readings in the -30 to -35 range possible over central and east-
central Wisconsin. Given high forecast confidence in -20 to -30 wind
chills areawide through Tuesday morning, elected to extend the Cold
Weather Advisory for all of southern Wisconsin until 12 PM CST
Tuesday. Given the potential for wind chills at/below -30 in central
and east-central Wisconsin, did consider issuing an Extreme Cold
Watch, but ultimately elected to hold at an advisory in these
locations given uncertainties in the duration and coverage of
warning level wind chills. Subsequent shifts will monitor trends,
with possible upgrades to Extreme Cold Warnings possible in later
forecasts should forecast confidence continue to increase.

Tuesday Night: Frigid wind chills will continue, though they won`t
be nearly as cold as readings occurring earlier in the period.
Widespread -10 to -20 values are expected, with some potential for
additional advisories over central and east-central Wisconsin. Will
monitor trends over the coming forecasts.

Quigley

&&

.LONG TERM...
Issued 451 AM CST Sun Jan 19 2025

Wednesday through Saturday:

Synopsis: One final frigid morning is forecast on Wednesday. Despite
the chilly start, air temps will quickly begin to trend upward by
Wednesday afternoon as surface winds turn southwesterly ahead of low
pressure in the Canadian Prairies. Said surface low will be
accompanied by an upper disturbance, which is forecast to progress
across the western Great Lakes during the day on Wednesday. Lift
affiliated with the disturbance may support some light snow showers
throughout the day on Wednesday, with accumulations appearing light
at this time. Temperatures will hover near or just below normal
through the end of the week with generally westerly surface flow
prevailing across the western Great Lakes.

Wednesday & Wednesday Night: In coordination with surrounding
offices, inserted some slight chance (~15-20%) precip probs
along/ahead of the disturbance moving in from the Northern Plains.
Early signals point toward accumulations being light (< 1") in this
potential round of light snow, though trends will be monitored over
the coming forecasts.

Quigley

&&

.AVIATION...
Issued 936 AM CST Sun Jan 19 2025

Gusty west northwest winds are expected to continue into Monday
across area terminals. There is an area of scattered to
sometimes broken stratocumulus across Madison and Janesville,
which may lead to ceilings around 1500 to 2000 feet AGL at times
into this afternoon. Otherwise, VFR conditions are expected into
Monday, with clouds gradually increasing.

Wood

&&

.MARINE...
Issued 936 AM CST Sun Jan 19 2025

Breezy west northwest winds continue across the open waters
today, as low pressure around 29.4 inches remains nearly
stationary over far northern Quebec and northeastern Hudson Bay.
Arctic high pressure around 31.0 inches will settle into the
northern Rocky Mountains tonight, drifting south into the
central Rocky Mountains Monday through Tuesday. The progression
of the high will help to maintain breezy west northwest winds
across Lake Michigan through the first half of this week.

The breezy west northwest winds will combine with elevated wave
heights and frigid air temperatures to support heavy freezing
spray from this afternoon through Tuesday afternoon. Heavy
Freezing Spray Warnings remain in effect for the southern half
of Lake Michigan from Noon CST today through 3 PM CST Tuesday.
It is possible that areas of heavy freezing spray could continue
into Tuesday evening over portions of the warned area, with
trends being monitored over coming forecasts for any potential
extensions.

Low pressure around 29.5 inches will move south into the
Canadian Great Plains Tuesday night into Wednesday, promoting a
southwest wind shift over Lake Michigan. Southwest winds could
be breezy Wednesday afternoon. This will support continued
freezing spray potential into Wednesday afternoon, with any
freezing spray expected to be lighter relative to earlier in the
week.

Breezy west northwest winds and elevated wave heights will
continue this afternoon through Monday in nearshore zones. These
values will approach Small Craft Advisory levels at times.
Trends will be monitored into this afternoon, with headlines
being issued should forecast confidence increase.

Quigley/Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Cold Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
     WIZ057-WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-
     WIZ067-WIZ068-WIZ069-WIZ070 until noon Tuesday.

     Cold Weather Advisory...WIZ066-WIZ071-WIZ072...6 PM Sunday to
     noon Tuesday.

LM...Heavy Freezing Spray Warning...LMZ080-LMZ567-LMZ669-LMZ671-
     LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...noon Sunday to 3 PM Tuesday.

&&

$$

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