421
FXUS63 KGRB 242201
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
401 PM CST Mon Nov 24 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Rain, low clouds and fog continue this evening, and persist
  through Tuesday.

- Significant accumulating snow is likely over northern Wisconsin
  late Tuesday night into Thursday, with heavy snow expected in
  Forest, Florance, Oneida, and Vilas Counties. A Winter storm
  Watch has been issued for these County. Additional winter
  weather headlines may be needed for counties further and and
  east across central and far northeast WI.

- Strong northwest winds will gust to 25 to 40 mph Wednesday into
  Thursday. A Gale Watch has been posted for Lake Michigan,
  including the bay.

&&

.DISCUSSION...
Issued at 401 PM CST Mon Nov 24 2025

Rest of today through Tuesday...

Low pressure system currently centered over central Kansas will
continue to bring more mild and moist air for the remainder of
today. This will result in the arrival of light rain spreading from
south to north this evening. Along with the rain increasing low-
level moisture may result in areas of fog overnight, mainly across
central Wisconsin. As the low continues to lift into the upper-
Mississippi Valley Tuesday the deformation zone should lift into
northern WI Tuesday morning bringing a brief dry period south of HWY
29 while steady rain continues across north-central WI through most
of Tuesday. Overall impacts through this period of the forecast
should be minimal

Winter Storm and Lake Effect Snow Tuesday night to Thursday...Models
continue to indicate that the resident low over the region will phase
with a digging trough late Tuesday spurring on a period of rapid
cyclogenesis over MN. This surface low will then make its way across
WI Tuesday night into Wednesday. As winds turn to the northwest on
the backside of this system much colder air will push into the
region causing a change over from rain to snow. This transition is
expected to beginning across north-central WI after sunset Tuesday,
while areas in the Fox Valley and near the lakeshore may not
transition until early to mid morning Wednesday. The forecast track
of the low has shifted slightly further south compared to previous
cycles which may increase north-central WI time under the TROWL.
This has resulted in an increase in snowfall amounts across north-
central WI and prompted an expansion of the Winter Storm Watch to now
include Forest, Florance, and Oneida counties where 4-8" of snow is
now forecast. Snowfall amounts across Vilas Co. have also increased
with 12-18" now expected across the northwest part of the county due
to a prolonged period of lake enhances snowfall Wednesday through
much of Thursday. There is ~40% that the far northwest part of the
county exceeds 18" of snow by the time the lake effect snow comes to
an end Friday morning. South of a Merrill to Iron Mountain line
snowfall totals are expected to be much lower, generally ranging from
just a trace in east-central WI to 1-3" in central and far northeast
WI.

Along with the snow CAA and a tightening pressure gradient will
result in strong northwest winds Wednesday into Thursday. The
strongest winds are expected across the Fox Valley and lakeshore
where NBM shows 50-80% chances for gusts over 40 mph Wednesday
afternoon. The strong winds will likely create area of blowing and
drifting snow and periods of greatly reduced visibility making
travel difficult and hazardous at times. Additional behind the cold
front Wednesday convective roll type snow showers may develop over
portions of the region which could result in Snow Squall like
conditions at times. A flash freeze is also possible in and around
the Fox Valley Wednesday evening as temperatures quickly fall from
the mid 30s into the mid 20s. Any wet roads that are untreated could
quickly become ice covered and slippery.

Those traveling for the Thanksgiving holiday or the gun deer season
should monitor the forecast closely and consider making alternative
travel plans, especially if you are traveling through the Northwoods
Wednesday and Thursday.

Brief period of high pressure should bring a brief period of dry and
calm weather to the region Friday.

Weekend Snow Chances...Long range ensembles show an inverted surface
trough moving out of the intermountain west late this week and
tracking across the western Great Lakes this weekend. With the
passage of this feature the NBM shows broad 20-30% chances for at
least 2 inches of snow Saturday into Sunday with the highest probs
across the Fox Valley and lakeshore areas. However, there is still
considerable spread within the ensembles as the 10th percentile
snowfall shows well under 1" while the 90th percentile shows some
locations across eastern WI could see up to 4".

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1130 AM CST Mon Nov 24 2025

Mix of MVFR/VFR conditions this afternoon as mid and high clouds
continue to push into the region as a low pressure system centered
over Kansas advects higher moisture levels into the region. Upstream
IFR clouds and vsbys are being observed across Iowa and SE
Minnesota. As the low continues to into the middle Mississippi Valley
the low clouds and light rain should lift into central WI late this
afternoon (after 23Z). IFR conditions will then spread over the rest
of the region this evening/overnight. Along with the low clouds the
combination of light rain and fog should results in periods of
MVFR/IFR vsbys overnight into Tuesday morning. AUW, CWA, and RHI
have the highest probabilities (20-30%) of see vsbys drop below
1SM. Areas south of a AUW to GRB line should see a brief break in
the rain Tuesday morning, however, rain will return during the
afternoon. Beyond the TAF period expect a transition to from rain to
snow late Tuesday night into Wednesday as much colder air dives into
the region. Along with the change over to snow northwest winds are
expected strengthen Wednesday with gusts reaching 35-45 mph.

&&

.MARINE...
Issued at 401 PM CST Mon Nov 24 2025

Probabilistic forecasts are now showing a 70-95 percent chance of
northwest gales on Lake Michigan Wednesday into Thursday. A Gale
Watch has been posted from 15z/Wed through 18z/Thu on both the lake
and bay.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Tuesday night through late
Wednesday night for WIZ005.

Winter Storm Watch from late Tuesday night through Wednesday
evening for WIZ010>012.
&&

$$

DISCUSSION.....GK
AVIATION.......GK
MARINE.........GK