110
FXUS63 KGRB 241732
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1132 AM CST Wed Dec 24 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- A period of freezing drizzle is possible this evening south of
  Highway 29, 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 349 AM CST Wed Dec 24 2025

Light Frozen Precipitation Potential Early Today & This Evening:
Precip struggling to develop across northern WI early this morning
associated with weak WAA and FGEN due to dry air below 800mb. The
dry air looks to win out through sunrise, with only a stray
flurry/ice pellet possible near the MI border early today with no
impacts. The dry air will also be present further south, which
will delay/limit how much drizzle or freezing drizzle occurs later
this afternoon and evening. A push of better saturation does
arrive around sunset across central and east central WI. This
should allow some light precip to develop south of Hwy 29. The
better saturation will be along/south of Hwy 10, which is where
the best chances to see this light precip activity, peaking
between 6-10pm. Surface temps will be slowly dropping through the
evening, so any drizzle could turn into some freezing drizzle,
along with any wet spots freezing. Some minor travel impacts will
be possible, mainly on untreated roads and surfaces after sunset.

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%. The system is
fairly progressive, with model consensus of up to 0.1" of icing in
most spots (probabilities of greater than 0.1" under 20%).
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, with the WSSI only showing 20-30% chance of minor winter
impacts. 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 18Z TAF Issuance
Issued at 1132 AM CST Wed Dec 24 2025

VFR conditions prevailed late this morning, with only a few MVFR
clouds over KMTW. Expect mainly VFR conditions this afternoon,
with some MVFR ceilings possible, especially near the lakeshore,
as lower clouds may develop with southeast flow. HREF showing
50%+ chances for a at least a 2-4 hr period of these lower clouds,
but confidence is low on if/how long these clouds will stick
around. Will have TEMPO group to handle these lower clouds at KMTW
as the coverage appears fairly limited. Another period of lower
clouds this evening (mainly MVFR) is possible from GRB southward,
along with some drizzle or freezing drizzle, as a little better
moisture arrives. Yet another area of low clouds will work south
towards RHI early Thursday morning. Otherwise, look for mid and
high clouds to spread across the region.

Light southeast winds will gust to around 15 kts early this
afternoon, then become light and variable in the late afternoon
and evening. Winds shift to the north overnight but remain under
around 10 kts. Winds shift again to the east or northeast
Thursday morning with gusts to 15 kts.

&&

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

&&

$$

DISCUSSION.....Bersch
AVIATION.......Kurimski

NWS GRB Office Area Forecast Discussion