460
FXUS63 KGRB 250459
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1059 PM CST Wed Dec 24 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- A period of freezing drizzle is possible this evening south of
  Highway 10, leading to slippery travel conditions.

- An impactful period of mixed wintry precip expected Thursday
  evening/night through Friday morning. Icing will be the primary
  threat, especially north and west of the Fox Valley.

- Temperatures will remain above normal most of the week, then a
  shot of much colder air arrives late this weekend, with high
  temperatures falling into the single digits and teens by Monday.

- Gusty east-southeast winds could lead to ice floes on Green Bay
  Thursday afternoon into Friday morning. West-northwest gale
  force winds possible Sunday into Monday.

&&

.DISCUSSION...
Issued at 227 PM CST Wed Dec 24 2025

Light Frozen Precipitation Potential This Evening: Model trends
continue to push the chance for drizzle/freezing drizzle south
this run, with model soundings showing a small window of a few
hours (1-3) of drizzle/freezing drizzle this evening, mainly
south of a line from Wisconsin Rapids, to Appleton, to Two Rivers.
Given the small window of a few hours, any travel impacts should
be minimal.

Wintry Mix & Icing Thursday night and Friday: After a quiet
Christmas Day, wintry precip will spread east across the area
Christmas evening/night into Friday morning as a 30-40 kt LLJ
ushers in a surge of moisture and WAA arrives, along with a weak
shortwave traversing the state and low pressure working through
the southern Great Lakes. A pronounced warm nose between 850-
700mb (as warm as 5-6C) will be present for much of the evening,
leading to freezing rain and sleet over much of central and north-
central WI where surface temps will reside below freezing. This
layer shrinks as you work towards the MI border, so more sleet
and snow is expected, but amounts should generally stay under an
inch with some freezing rain possible on top of it. In addition,
loss of ice crystal production is possible at times, leading to
some freezing drizzle. The greatest threat for icing is expected
north and west of the Fox Valley, where probabilities of ice
accumulations currently sit around 60-90%. Models have come in
with slightly higher amounts of ice this run, with model
consensus of up to 0.1" of icing in most spots and probabilities
of greater than 0.1" increasing to 20-40% north of Wausau.
Slightly warmer surface temps will be present in the Fox Valley,
aided by southeast winds coming off of Lake Michigan, which look
to keep the precip plain rain for most of the event. But a degree
or two colder could lead to more ice concerns in the Fox Valley,
plus with a cold ground, there could still be some icing concerns.
WSSI/WSO really not showing any significant impacts across the
region; however, the chance of minor impacts has increased to
30-60% north and west of the Fox Valley. Considering holiday
travel and really any amount of freezing rain can lead to some
issues on the roads, will likely need some kind of advisory for
parts of the area, but will hold off for now. The wintry mix will
slowly shift north Friday morning as slightly warmer air works
northward, with the precip ending by noon Friday for most
locations, with only a little drizzle or freezing drizzle
continuing in the afternoon.

Fog Potential: Light and variable winds, along with moisture near
the surface may lead to some very patchy fog overnight,
especially over northern WI. As mid-high level clouds continue to
increase early this morning, the fog threat should be held in
check. Some fog will be again possible this evening into tonight
as some minor melting of snow is expected through the day to give
a little bump in low-level moisture, but models are not in great
agreement on this potential. Best potential for the fog look to be
from late afternoon into the evening as winds remain light (and
even out of the south/southeast for a time in the Fox
Valley/lakeshore). As winds turn northerly through the evening,
the fog threat looks to lower/shift south.

Temperatures & Wind Chills: Above normal temps are expected for
much of the holiday week with highs mainly in the upper 20s to
around 40, with much colder air and gusty winds arriving Sunday
into Monday behind an arctic front. Highs on Monday look to be in
the single digits and teens. The gusty west to northwest winds
will drop wind chills below zero for most of the area Sunday
night into Monday, possibly approaching cold weather advisory
criteria.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1048 PM CST Wed Dec 24 2025

First round of MVFR CIGS will exit central and east-central
WI shortly after 06z. Attention then turns next batch of MVFR
CIGS moving southward into Vilas County shortly before 06z.
The low deck is expected to spread southward overnight due to
north/northeast winds. MVFR CIGS will likely prevail across
central and north-central WI on Christmas Day into Thursday night.
Across east-central WI, dry low level flow may allow CIGS to rise
into the VFR category later in the afternoon/early evening
before dropping into the MVFR category during the late evening.
For Thursday evening, a wintry mix is expected to develop late
in the evening across central and north-central WI from 03z-05z
and across northeast WI around 06z or shortly after.  A mix
of freezing rain/sleet/snow is anticipated north and west of
the Fox Valley. For the KGRB/KATW/KMTW taf sites, it will likely
be rain, freezing rain mixed with sleet at times.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Eckberg

NWS GRB Office Area Forecast Discussion