NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 080431
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1031 PM CST Sun Dec 7 2025

.KEY MESSAGES...

- Below normal temperatures continue through next weekend. Low
  temperatures tonight are expected to be near zero away from
  Lake Michigan.

- A broken line of lake effect snow may wobble onshore tonight,
  especially right along the shoreline of far southeastern WI.
  Generally less than 1 inch of snow is expected.

- Light snow is possible again Monday night, mainly north of the
  I-94 corridor. Expecting around an inch or less in these
  areas.

- A wintry mix is expected to develop Tuesday evening, with
  slick spots on area roads possible due to continued cold
  pavement temperatures. Wintry mix will transition to snow on
  Wednesday, with uncertainty remaining in total snowfall
  amounts.

- Additional rounds of snowfall are then possible through the
  end of the work week, but confidence in exact time frames is
  much lower.

&&

.UPDATE...
Issued 1030 PM CST Sun Dec 7 2025

Inland temperatures have dropped 2-5 degrees below prior
expectations this evening, with the nearly calm wind, snow
cover, and nearly clear skies optimizing radiational cooling.
Some thin high-altitude clouds have recently moved in and are
putting the brakes on the cooling trend, meanwhile lake effect
clouds in far southeastern WI have kept temperatures in check.

Radar has remained clear through this evening, though we are
finally seeing some weak returns over Lake Michigan to mark the
beginning of lake effect snow potential. Despite the late start
(likely arriving after midnight), shoreline areas of far
southeastern WI may yet see a trace to 1 inch snow accumulation
based on the latest 00z model guidance, though it's not a
guarantee. DGZ layer saturation is very small based on forecast
soundings, and there's dry air both above and beneath the lake
effect clouds. Overall precip chances are in the 40-60% range
for the immediate shoreline, much lower towards the western edge
of lakeshore counties. The SSW to NNE orientation of the lake
effect clouds as seen on Nighttime Microphysics Satellite RGB
indicates that areas north of Milwaukee county also have
relatively lower precip chances.

The light lake effect snow looks to remain just offshore over
Lake Michigan through around 10 AM CST Monday morning before
southwest winds kick in and push it further away.

Sheppard

&&

.SHORT TERM...
Issued 352 PM CST Sun Dec 7 2025

Tonight through Monday night:

A convergence band of lake effect snow is expected to develop
this evening as high pressure pushes in strongly from the
northern Plains and light easterly winds develop over Lake
Michigan. This band is expected to be weak and quick-moving, as
plenty of shear aloft is expected (straight easterly winds
between surface and 850 mb, and straight westerly above that
level), and high pressure bringing in plenty of dry air to
entrain within the band. Therefore, expecting only trace to an
inch of snowfall with this activity. Snow will meander on and
off shore from Kenosha County northward to Ozaukee and perhaps
Sheboygan through the overnight hours into Monday morning,
exiting offshore again shortly after sunrise. Meanwhile, Arctic high
pressure in the remainder of southern Wisconsin will produce low
temperatures near zero degrees overnight tonight. Light winds
will keep wind chills near the observed temperatures, so no
headlines will be needed.

Monday, expect southerly winds to develop ahead of a low
pressure system ejecting from the Canadian Prairies. Increasing
cloud cover is also expected. However, expecting southerly winds
to win out and bring highs in the mid 20s. As low pressure
propagates through northern Wisconsin, expecting a trailing
frontal boundary to produce at least some snow showers across
southern Wisconsin Monday evening through Monday night. Any
accumulations currently look to stay north of I-94 as the system
has continually trended northward, but will continue to monitor
trends and adjust as necessary. Regardless, around an inch or
less of accumulations is expected. Snow exits into Tuesday, with
winds shifting to westerly behind the front.

MH

&&

.LONG TERM...
Issued 352 PM CST Sun Dec 7 2025

Tuesday through Sunday:

Low pressure and a shortwave trough will exit the nrn Great Lakes
to the east on Tue, but a digging and amplifying shortwave trough
will move into WI Tue nt from the nrn Great Plains. There are
slight to modest timing and placement differences among the
ensemble means of the GFS, ECMWF, and Canadian models, but overall
it appears a 987 sfc low will track across central WI into lower
MI Tue nt. Low to mid level warm, moist advection will boost temps
at the sfc and aloft above freezing for a time, but possibly
remaining at or below freezing toward central WI. Thus pcpn type
will begin as rain/snow over much of the area becoming rain, then
back to light snow toward the end of the event. However, toward
central WI it is possible all snow could fall with a few inches of
wet snow accumulation. There also would be at least a slight
potential for freezing rain as the surface and pavement could
remain below freezing for a while even as the air temps warm above
freezing. Keep up with the forecast and Winter Wx Advisories may
eventually be needed for portions of srn WI.

Brisk nwly winds and cold advection will then take hold on Wed
with light snow coming to an end. Nwly flow aloft will continue
through the week with additional shortwave troughs in the vicinity
of WI bringing 20-30 percent chances for light snow most days.
This pattern will also lead to increasingly cold air including the
arrival of arctic air late in the week. Upper ridging and a sfc
ridge may finally arrive on Sunday.

Gehring

&&

.AVIATION...
Issued 1020 PM CST Sun Dec 7 2025

Lake effect clouds have built into portions of far southeastern
WI, resulting in MVFR ceilings around 2,000 to 2,500 feet. These
will persist at broken coverage through much of tonight in
these areas, and may briefly wobble deeper into lakeshore
counties or far southern Wisconsin (as seen at KJVL recently).
We still expect at least a few flurries / light snow showers out
of this lake effect activity, with a trace to 1 inch
accumulation possible for KENW, KRAC, and KMKE. Generally not
expecting this activity to reach other terminals (though KMWC
and KSBM are not completely out of the question). TAFs currently
afford the lake effect a PROB30 group, but we could upgrade to a
TEMPO once we have a healthy signature of it on radar. On the
other hand, if it fails to materialize, it could be dropped.

Predominantly VFR ceilings (between 3,500 and 10,000 ft)
expected throughout the day Monday, with a southerly breeze
gradually building. The next chance for snow is Monday evening
/ Monday night (20-50%), with trace to 1 inch accumulations
possible, mainly north of the I-94 corridor towards east-central
WI.

Sheppard

&&

.MARINE...
Issued 352 PM CST Sun Dec 7 2025

North-northwesterly winds will slowly diminish and becoming light
and variable tonight as high pressure builds across the Great
Lakes region. The Small Craft Advisory in the southern Wisconsin
nearshore regions will therefore end this evening.

High pressure exits Monday afternoon as low pressure tracks
through northern Minnesota into Lake Superior, bringing stiff
southwesterly winds gusting to gale force across the northern
open waters. Condition hazardous to small craft will develop in
nearshore regions Monday night and continue through Wednesday.
A Gale Watch is in effect late Monday night into early Tuesday
morning for the northern half of the open waters. A few gusts
near 40 kt are possible over the far northern portions. As low
pressure exits, expect winds to shift to become westerly through
the day Tuesday.

Another low from the northern Plains will shift winds to south-
southwest Tuesday evening, before the low crosses near the
center of Lake Michigan and brings strong southwesterly winds to
the southern half and light easterly winds to the northern half
overnight Tuesday. Winds will all shift to northwesterly as the
low exits into Wednesday, with gales possible in the southern
half throughout this time frame. Winds gradually diminish
Wednesday night, but remain northwesterly through the end of the
week. Conditions hazardous for small craft will develop in
nearshore regions again Thursday night through Saturday.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...10 PM Monday to 6 AM Tuesday.

&&

$$

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