244
FXUS63 KGRB 251809
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1209 PM CST Thu Dec 25 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- An impactful period of mixed wintry precip expected this evening
  into Friday morning. Greatest icing north and west of the Fox
  Valley, with a glaze further south/east.

- A light wintry mix, falling temperatures and gusty winds could
  lead to poor travel conditions Saturday night into Monday.

- 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 late Sunday into Monday.

&&

.DISCUSSION...
Issued at 436 AM CST Thu Dec 25 2025

Wintry Mix & Icing This Evening into Friday Morning: Christmas Day
will be dry for most/all of the daylight hours, then as a 30-40
kt LLJ ushers in a surge of moisture, WAA arrives, a weak
shortwave traverses the state and low pressure works through the
southern Great Lakes, precip will spread across the area starting
between ~00-06z. Pronounced warm nose between 850-700mb (as warm
as 5-6C) will be present for much of the evening into early
Friday, leading to freezing rain and sleet over much of central
and north-central WI where surface temps will reside below
freezing. This will create hazardous road conditions for post
holiday travelers for much of the area. Any snow looks to be
confined closer to the MI border as the warm nose shrinks, with
under an inch of snow expected. Could get some sleet accumulations
across the area depending on the eventual thickness of the warm
nose, which will likely cut into the freezing rain accums a bit.
The precip could start off as a little freezing drizzle before the
better saturation arrives, but impacts would likely be the same.
As the precip ends on Friday morning, another period of freezing
drizzle and drizzle is expected as dry air in the mid-levels
arrives and we lose ice crystal production. The greatest threat
for impactful icing will be just north and west of the Fox Valley
(70-100%), but probabilities of glazing is 50% further south.
Probabilities of greater than 0.1" of ice are quite low, with the
greatest values of ~25% along and just north of the Hwy 29
corridor. So have kept most ice totals below 0.1", but some
higher amounts closer to 0.2" are possible where the highest QPF
overlaps the coldest air, which looks to be along and just north
of Hwy 29. As you head south, especially near Hwy 10 and near Lake
Michigan, surface temps may stay just above freezing through the
event, but with ground/road temps at/near freezing, no insolation
from the sun, leaned on the safe side and included them in the
advisory, with lower amounts and a shorter timeframe. Road issues
in the lakeshore counties will likely be away from the shoreline,
as southeast winds will keep temps warmer near the lake (water
temps in the upper 30s to around 40). Tried to not get too cute
with the headlines, but with different onset/end times, and the
far south having less icing and switching over to rain much
earlier than others, went with the 4 zones.

Wintry Mix & Gusty Winds Saturday Night into Monday: Another
round of light mixed precip is scheduled to arrive late Saturday
as another low pressure and arctic front move across the Great
Lakes. Temps are forecast to be warm enough for rain at the onset,
but a change over to mixed precip, including freezing rain,
Saturday night into Sunday morning. The mixed precip will change
over to a quick shot of light snow on Sunday as the arctic front
pushes through. The wintry precip could lead to another period of
hazardous travel. Very gusty winds will arrive behind the arctic
front Sunday afternoon into early Monday, with NBM probabilities
showing 30-60% of 35+ mph winds. The wintry precip, some possible
blowing/drifting snow, and temps crashing along/behind the front,
could lead to some travel/icing issues on the roads.

Temperatures & Wind Chills: Above normal temps will continue for
much of the holiday week with highs mainly in the upper 20s to
around 40 (with a few mid 20s today in north-central WI). Much
colder air and gusty winds arrive Sunday into Monday behind an
arctic front. Highs on Monday look to range from around 10-20F.
The gusty west to northwest winds will drop wind chills below zero
for most of the area Sunday night into Monday. Latest guidance has
wind chills above cold weather advisory criteria.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1209 PM CST Thu Dec 25 2025

Mid to high clouds prevailed across the entire area while a
shallow layer of MVFR clouds were spreading across east-central WI
and along the lakeshore from onshore flow. Given this MVFR cloud layer
is very shallow, it is very possible it will scattered out over
the next few hours. However, did not feel confident enough to
include this at the east-central WI TAF sites.

By this evening, clouds will lower and thicken to MVFR and
eventually IFR/LIFR as a wintry mix spreads across the region.
Mainly freezing rain and freezing drizzle are expected at the
central and north-central WI TAF sites, while mainly rain and
drizzle are anticipated at the east-central WI TAF sites. It`s
possible some freezing rain may mix with the rain over the east-
central WI TAF sites at times as well.

This afternoon`s easterly winds gusting to 15 to 25 kts will
become southeasterly this evening, as gusts to 25 kts continue. A
period of LLWS is also expected in north-central WI this evening.
Surface winds will subside Friday morning.

&&

.MARINE...
Issued at 436 AM CST Thu Dec 25 2025

Gusty northeast winds will shift to the east this afternoon then
to the southeast tonight and continue into Friday morning. On Lake
Michigan, gusts 25 kts are expected, with waves building to 3-6
ft today and to 4-8 ft tonight. Have expanded the current Small
Craft Advisory northward. On the bay, ice coverage and colder
water temps will limit gusts and wave action (to mainly under 3
ft), but some funneling could produce a few gusts to 25 kts. Have
held off on a Small Craft Advisory for the bay but will monitor
wind trends. Gusty northwest winds are forecast behind the arctic
front Sunday evening into Monday morning, with gale force gusts to
40 kts possible. Freezing spray will also be possible, especially
near Deaths Door and toward the open waters of Lake Michigan.

As winds become east/southeast, the threat for ice floes will
increase on the bay, as recent satellite imagery shows broken ice
coverage in the southern bay. The ice will be pushed toward the
Marinette/Oconto shoreline. Then, the gusty west winds this
weekend will push this ice back towards the Brown/Kewaunee/Door
shoreline.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM this evening to noon CST
Friday for WIZ005-010>013-018-019-021-073-074.

Winter Weather Advisory from 9 PM this evening to 9 AM CST
Friday for WIZ020-022-031-037>040.

Winter Weather Advisory from 6 PM this evening to 9 AM CST
Friday for WIZ030-035-036-045.

Winter Weather Advisory from 9 PM this evening to 6 AM CST
Friday for WIZ048>050.
&&

$$

DISCUSSION.....Bersch
AVIATION.......Kruk
MARINE.........Bersch

NWS GRB Office Area Forecast Discussion