464
FXUS63 KGRB 301201
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
601 AM CST Tue Dec 30 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A clipper system brings a round of fluffy snow today into early
  tonight. An inch or less is likely for most, with 1 to 2 inches
  expected in the Fox Valley, bayshore and lakeshore areas. Minor
  travel concerns are expected.

- An arctic cold front will bring additional light snow on
  Wednesday, with a dusting to a half inch anticipated most areas.
  A couple inches of snow will be possible in Vilas County due to
  lake-effect.

- Wind chills as cold as 15 to 25 below zero are possible New
  Years Eve night into Thursday morning.

&&

.DISCUSSION...
Issued at 324 AM CST Tue Dec 30 2025

Low clouds and flurries persisted over north central and far
northeast WI early this morning, as mid-level clouds increased
regionwide due to WAA ahead of an approaching clipper system.
The regional radar mosaic showed light snow developing over
eastern ND and northwest MN.

Clipper System Snow: WAA ahead of the approaching clipper will
generate patchy light snow or flurries across the area later this
morning, but snow should pick up a bit this afternoon as a short-
wave trough and LFQ of a 110 kt jet streak arrives. This system
seems to get its act together as it moves into eastern WI, with a
more concentrated area of lift developing within the dendritic
growth zone. Most areas should see a half inch to an inch of snow,
but the Fox Valley, bayshore and lakeshore areas could get 1 to 2
inches. This will produce slick roads, especially in eastern WI,
for the evening commute.

Arctic Cold Front Snow: An arctic cold front will move into
northern WI late tonight, then drop south through the region
during the day on Wednesday. As this occurs, conditions will
become more favorable for lake-effect snow (NW winds and
increasing instability over western Lake Superior) in NC WI, with
accumulations of 1 to 3 inches possible in Vilas County. Despite
the arrival of a dry arctic air mass, have opted to boost pops
across the forecast area given fairly strong dynamics with the
frontal passage, increasing FGEN, a short-wave and the LFQ of a
135 kt jet streak. Outside of the lake-effect region, only
expecting a dusting to a half inch of powder in most areas.

Brief Period of Cold: A fairly strong push of cold air arrives in
the wake of the arctic front, with H8 temps dropping to -18 to -23
C across the region later Wednesday into Wednesday night. The
combination of temperatures falling into the single digits below
zero (except near Lake Michigan) and persistent NW winds will
result in wind chills of 15 below to 25 below zero late Wednesday
night into Thursday morning. Wind Chill Advisories may eventually
be needed for roughly the northwest half of the forecast area.
Some moderation in H8 temperatures occurs Thursday into Thursday
night, and cloud cover should prevent another big nighttime drop
in temperatures, so wind chills should not be as low Thursday
night into Friday morning.

Rest of the Forecast: No significant precipitation events are
expected for the rest of the extended forecast period. After the
brief shot of arctic air, a gradual moderate in temperatures is
expected, with highs reaching the 20s by Sunday/Monday.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 551 AM CST Tue Dec 30 2025

MVFR ceilings were still being observed over NC WI (including RHI) early
this morning, but had recently moved out of AUW. Elsewhere, mid-level
clouds covered the region. Light snow was approaching from MN, in
response to an incoming Alberta clipper low pressure system.

Light snow will overspread the region late this morning, with
mainly MVFR ceilings/vsbys. Potentially more significant snow
should impact the region from mid-afternoon through early evening,
with periods of IFR vsbys expected. The snow should taper off
from west to east in the evening, though some lake-effect snow
could persist in far NC WI.

Winds will be from the W-NW with speeds of 10 knots or less.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......Kieckbusch

NWS GRB Office Area Forecast Discussion