NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 261035
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
435 AM CST Fri Dec 26 2025

.KEY MESSAGES...

- Patchy dense fog (1/4 mile or less) is expected west of
  Madison this morning, with fog and visibilities as low as 1
  mile developing elsewhere. Fog will lift this afternoon, but
  may return late tonight.

- Warm temperatures and rain on Sunday will transition rapidly
  to snow and temperatures below freezing Sunday night, with
  flash freeze possible. Expect widespread accumulations between
  a trace and an inch, but areas near central Wisconsin may see
  as much as 3 inches.

- Polar air returns Sunday night and continues through the end
  of next week, with temperatures remaining at or below normal.

- Northwest gales are likely for all of Lake Michigan Sunday
  night into Monday evening.

&&

.SHORT TERM...
Issued 435 AM CST Fri Dec 26 2025

Today through Saturday:

Low clouds and rain showers will continue through early this
morning, with fog developing behind the rain showers shortly
before sunrise and continuing into midday. Fog density upstream
has been in the 1/2 to 1/4 mile visibility range, but expecting
visibilities to improve shortly after sunrise to around 1 mile.
Still potential for areas of dense fog, however, and conditions
will be monitored for any developing hazards. Fog will likely lift
briefly this afternoon.

Low clouds will linger throughout the afternoon, preventing
temperatures from rising higher than the mid-40s in the south and
the upper 30s in the north, even with a warm airmass in place. A
cold front will sweep through the region this afternoon, bringing
a return to the mid-30s during the afternoon to evening hours.
Temperatures will stabilize overnight with low clouds
continuing, keeping lows in the mid-30s. Fog may build back down
to the surface tonight as well, as winds diminish under a ridge
of weak high pressure.

Saturday, expect winds to shift to southeasterly once again as low
pressure develops in the lee of the central Rockies between a
northern shortwave ejecting southeastward from Canada and a
developing southern shortwave from the remnants of an earlier
atmospheric river in California. As these shortwaves interact,
expecting low pressure to develop and begin to propagate
northeastward into Saturday night. Expecting highs in the mid-40s
under the continual surface WAA, even as skies remain generally
overcast.

MH

&&

.LONG TERM...
Issued 435 AM CST Fri Dec 26 2025

Saturday night through Thursday:

As low pressure ejects from the Rockies into the Plains on
Saturday night, expecting southeasterly winds to continue, with
low temperatures remaining in the upper 30s to low 40s. Low
pressure will make its closest approach on Sunday, although model
solutions still diverge on the strength and placement of the low
center due to the uncertainties of how the northern shortwave with
phase with the southern shortwave (which still looks to become the
dominant one). Still, expecting widespread rainfall (~60%
chances) as the low makes its closest approach as well as high
temperatures in the mid to upper 40s. A few spots in far southern
Wisconsin may see highs near 50 degrees. During the afternoon to
early overnight hours, a strong cold front will drop temperatures
rapidly below freezing. This rapid drop in temperatures will also
transition any lingering rain to snow. Currently expecting
widespread accumulations of a dusting to an inch, with potential
for up to 3 inches in central Wisconsin. Regardless of exact
amounts, untreated wet surfaces will become slick as temperatures
fall overnight. Lows in the mid teens to near 20 degrees are
expected.

A few lighter snow showers may linger into Monday morning. Main
concern will be gusty northwest winds as low pressure occludes to
the northwest. Currently expecting gusts around 35 mph. However,
depending on the timing of the low and its intensity as it
occludes, higher gusts may become possible. Expect wind chills in
the single digits throughout the day, with temperatures in the low
20s. Winds will slowly diminish Monday night as low pressure exits
into Quebec.

The next chances for precipitation develop Tuesday as an Alberta
clipper rides along the Upper Midwest ridging into northern
Wisconsin. Currently expecting the majority of precipitation to
remain north of the forecast area (~15% chances in southern
Wisconsin).

A shift in the forecast pattern then develops for the latter half
of next week as the occluded low over Quebec retrogrades into the
Hudson Bay and an atmospheric river impacts British Columbia and
the Pacific Northwest. Expecting the combination of these two
major weather systems to bring in progressively colder air from
the Canadian Prairies, with highs in the teens by Thursday.

MH

&&

.AVIATION...
Issued 435 AM CST Fri Dec 26 2025

IFR ceilings are expected across the entirety of southern
Wisconsin by sunrise, with some pockets of LIFR visibilities
and ceilings, especially in southwestern Wisconsin and along the
IL/WI border. Patchy dense fog is expected in southwestern
Wisconsin as rainfall ends, with visibilities in the 1-3 SM
range elsewhere. Visibilities will improve midday, but expecting
IFR ceilings to continue with only minor improvements this
afternoon. Tonight, fog may build back down to the surface
during the late overnight hours, lifting into Saturday morning.

Southeasterly winds will become light and variable this morning,
then northwesterly this afternoon as a cold front moves through
the region. Light and variable winds are expected again overnight,
before becoming southeasterly again Saturday morning.

MH

&&

.MARINE...
Issued 435 AM CST Fri Dec 26 2025

Low pressure over the Upper Mississippi Valley to western Lake
Superior will continue to progress eastward today, bringing modest
southeasterly winds to Lake Michigan this morning, transitioning
to light and variable this afternoon before a cold front shifts
winds to northwesterly this evening into tonight. High pressure
builds in briefly tonight into Saturday, with light and variable
winds again.

Modest southeast winds will then return by midday Saturday and
continue through Sunday morning as low pressure develops over the
central Plains. Low pressure deepens Saturday evening and crosses
southern Lake Michigan, bringing gusty northwesterly winds up to
gale force. The low will continue to deepen throughout Monday as
it moves eastward. Confidence is high in gale force winds through
Monday night across the open waters, with brisk northwest winds
then continuing through Tuesday. Much colder air will also bring
moderate freezing spray throughout the gale time frame.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 2 PM
     Friday.

&&

$$

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