718
FXUS63 KMKX 152112
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
312 PM CST Mon Dec 15 2025

.KEY MESSAGES...

- Above average temperatures develop Tuesday afternoon through
  Thursday, with highs in the middle to upper 30s.

- The next chances for precipitation (60 to 80 percent) develop
  late Wednesday night into Thursday morning. Initial stages may
  be a mix of snow and rain, becoming all rain by midday
  Thursday. A transition to light snow is expected Thursday
  evening (~20% chance).

- Significantly colder temperatures in the single digits
  expected to develop Thursday evening, freezing any surfaces
  that remain wet from Thursday`s rain and snow.

&&

.SHORT TERM...
Issued 313 PM CST Mon Dec 15 2025

Tonight through Tuesday night:

High clouds and southwesterly breezes will continue throughout
tonight. Expecting highs in the low 20s this afternoon, with lows
in the upper single digits to low teens overnight.

Light and variable winds are expected overnight, which may lead
to areas of fog in southwestern to south-central Wisconsin
overnight as temperatures fall toward the dew points. With WAA
occurring in the mid levels of the atmosphere during the overnight
hours as well, any mixing from aloft will actually serve to
increase dew points at the surface, allowing any fog that does
develop to linger through the overnight hours. Inversion is
expected to be very shallow, with snowpack expected to be the main
influence on how low temperatures can fall tonight. Still some
uncertainty with fog density, especially going into the early
morning hours as mixing increases. Will monitor through tonight
for areas of potentially dense fog, but currently most concern is
in far southwestern Wisconsin.

As mixing increases into Tuesday, expecting fog to generally rise
to become low clouds. However, with WAA over frozen ground, may
see reduced visibilities continue through at least the morning
hours and potentially even later. Highs on Tuesday are expected to
be in the mid-30s, leading to snow melt and therefore inclusion of
additional water vapor into the air. Will continue to update the
forecast as confidence in the evolution of this setup increases.

Overnight Tuesday, temperatures fall back toward dew points again,
with lows in the mid-20s. Southwesterly winds will shift
northwesterly overnight, so any fog development overall is less
likely than tonight.

MH

&&

.LONG TERM...
Issued 313 PM CST Mon Dec 15 2025

Wednesday through Monday:

Northwesterly breezes as low pressure exits to the northeast, then
a ridge of high pressure will nudge northward again during the
afternoon hours, allowing for light and variable winds, decreasing
sky cover and bringing high temperatures in the mid-30s.
Meanwhile, expecting an atmospheric river pointed into the Pacific
Northwest to trigger low pressure development in the lee of the
Alberta and Montana Rockies. This low is expected to be steered
north of the high pressure in the Southeast U.S. Wednesday night
into Thursday, keeping southern Wisconsin within the warm sector.
A mix of rain and snow is expected (~60% chances) early Thursday
morning along a prefrontal precipitation region, likely
transitioning to all rain (60-80% chance of precipitation) by
midday as gusty southwesterly winds bring strong WAA to the
region. Expecting highs around 40 degrees.

As low pressure exits into eastern Quebec into Thursday night,
expect winds to shift to northwesterly, with intense CAA bringing
a return to all snow (~25% chance of precipitation) and potential
for a rapid refreezing of any remaining wet roads. Lows Thursday
night are expected to be in the single digits. Only light snow
accumulations are expected, as the low and forcing exit eastward.
Remaining snow showers exit by Friday morning.

An up-and-down pattern continues Friday through Monday as the
atmospheric river continues to impact southern British Columbia
and the Pacific Northwest, allowing for multiple clipper systems
to propagate across southern Canada and the northern Great Lakes
regions through the weekend. With high pressure remaining dominant
over the Eastern Seaboard, expecting the majority of precipitation
with these systems to remain across northern to central Wisconsin.
However, multiple shifts between southerly and northerly winds
will keep temperatures variable through the weekend into early
next week.

MH

&&

.AVIATION...
Issued 313 PM CST Mon Dec 15 2025

VFR ceilings are expected to continue across the area through
tonight. However, areas of fog may develop across southwestern to
south-central Wisconsin overnight as winds diminish and moisture
increases across the region. Currently remain uncertain in
potential for dense fog, but confidence has increased in at least
MVFR conditions from MSN to JVL south and westward. Adjustments
will be made as necessary for TAF purposes tonight. Winds will
become southwesterly and begin to increase early Tuesday morning,
with gusts of 20 to 25 kt expected starting midday Tuesday. This
will help to reduce fog density across the region, but will also
bring in a more moist airmass over snowpack. Therefore, may see
additional drops in visibility lingering into Tuesday and even
Tuesday night. Gusty winds will continue through Tuesday night,
with a cold front shifting winds to northwesterly and bringing an
end to any lingering fog concerns.

MH

&&

.MARINE...
Issued 313 PM CST Mon Dec 15 2025

Southwest wind will continue to diminish this evening into tonight
as a weak low over Lake Superior moves northeast. Light south
to southwest winds are expected through Tuesday morning before
increasing ahead of approaching strong low pressure. This low
will move east across Canada from central Saskatchewan into
northern Ontario Tuesday afternoon through Tuesday night.
Southwest winds will increase across the lake with gales likely
across the northern third as the low passes to the north. A Gale
Warning is in effect for the northern third during this time. In
nearshore regions, a Small Craft Advisory is in effect.

A cold front will cross the lake Tuesday night with winds veering to
westerly behind the front. Gusty west to northwest winds will
be short lived and will diminish behind the front Tuesday night.
Another strong low pressure system is expected to track
eastward along the Canadian border Wednesday into Thursday.
Winds will turn southerly and remain light Wednesday morning
before increasing. Strong southerly wind will develop ahead of
the low Wednesday night. Strong winds will veer Thursday morning
as another cold front crosses the lake and becomes west-
northwesterly. Southerly gales Wednesday night and west-
northwest gales Thursday afternoon through Thursday night are
likely. Brief periods of gales are possible in nearshore regions
as well.

Patterson/MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563...10 AM Tuesday to
     3 AM Wednesday.

     Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...9 AM
     Tuesday to 6 AM Wednesday.

&&

$$

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