705
FXUS63 KGRB 111738
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1138 AM CST Thu Dec 11 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Light snow likely Friday. Though snow accumulations will be
  under an inch, the snow may result in locally slick travel.

- Bitter cold this weekend. Daytime highs struggle to reach zero
  over much of central WI on Saturday. Wind chills as low as 20 to
  30 below zero Friday night and Saturday night. Cold weather
  headlines will be needed.

- Temperatures rebound next week.

&&

.DISCUSSION...
Issued at 346 AM CST Thu Dec 11 2025

Bitter cold this weekend is primary hazardous weather into early
next week. Also, light snow Friday afternoon could cause slippery
travel in some areas.

Near term through tonight...NW flow in wake of the clipper system
is bringing a few flurries to Door County and the lakeshore early
this morning, with some clouds over the north and east. Expect
the low clouds to gradually clear out later this morning. Colder
today with highs mainly in the teens. Mid clouds increase this
afternoon ahead of plains shortwave trough/warm front and banded
snow. Bulk of snow remains well to the south, but enough lift and
moisture in DGZ on the northern edge of system this evening to
produce flurries in central WI.

Light Snow Friday...

Arctic front driving south across Alberta and Saskatchewan early
today reaches the northern Plains late tonight, and crosses WI on
Friday afternoon. The front with increasing lift in the DGZ will
be sufficient to squeeze out light snow and flurries region-wide.
Snowfall will be less than 1" but could lead to slippery travel.
SW winds shift NW and will become gusty into Friday evening.
Probabilities are 70-90 percent central to east-central WI for
seeing gusts over 30 mph which may lead to some blowing, drifting
of any fresh snow. Snow tapers quickly Friday evening as the front
exits east.

Hazardous Cold This Weekend...

Bitterly cold airmass with 850mb temps down to -25c sweeps across
the western Great Lakes this weekend. Peak of cold is Saturday.
Highs on Saturday will struggle to reach zero in central WI, and
even toward the Fox Valley. Maybe Door County will see double
digit highs. Nowhere else though, even along the lakeshore. These
values will be at least 30 degrees below normal. Bitter cold wind
chills of 20 to 30 below zero are expected on Friday Night, then
again on Saturday night. At the least, Cold Weather Advisories
will be needed. But, risk of falling to Extreme Cold Warning
criteria has also increased slightly for Friday night compared to
what data showed 24 hr ago. Chances of seeing wind chills as low
as 35 below zero over central WI are 35-55%, and are 30-40% Fox
Valley to the lakeshore where criteria is 30 below zero. Due to
potential for more clouds dropping across with shortwave trough,
potential for reaching warning thresholds Saturday night are less
than 15% across the entire area. Pretty impressive cold
considering we are only into mid December.

Temps on the rebound next week with small precip chances...

What goes down must come up. That occurs in this case as sharply
negative 850mb temp anomalies this weekend are replaced by sharply
positive anomalies Tuesday- Wednesday of next week. Last time we
hit freezing at GRB was November 26th. Appears we`ll break this
streak by Wednesday, when forecast points to highs in the mid 30s.
Higher range of NBM highs suggests it could even occur on
Tuesday. We`ll have to see if this warmup will bring any of the
typical warmup over cold ground/snowpack issues we can see such as
fog and/or "non traditional" freezing rain or drizzle (occurs even
as air temperatures are slightly above freezing since ground is
still quite cold). Leading warm air advection may produce some
light snow Sunday night into Monday especially north. Next chance
of precipitation would be midweek, with some potential for a
wintry mix, before colder air returns. Plenty of time to sort out
these details.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1138 AM CST Thu Dec 11 2025

Stratus continues to cause headaches in the aviation forecast late
this morning. The stratus is holding tough over far northern and
eastern Wisconsin with MVFR and patchy IFR ceilings. Isolated
flurries are also occurring near the Upper Peninsula border.

It`s rather difficult to pinpoint if and when the low stratus will
dissipate despite high pressure moving into the region tonight.
Light north flow off Lake Superior will continue into the evening
before the trajectories back to become more westerly late tonight.
Generally show that stratus erodes at RHI/GRB/ATW/MTW late this
afternoon or early this evening. Confidence is low with the
timing.

Some guidance depicts patchy fog developing over the Fox Valley
and low stratus developing over central WI late tonight, but
there is hardly a consensus. Added scattered IFR ceilings to the
central and east-central WI TAF sites along with 6sm br.

Looking ahead, the arrival of an arctic front on Friday will
result in light snow (less than 1") late Friday morning through
Friday afternoon. Vsby as low as IFR may accompany the snow while
cigs will be MVFR-IFR. Light SW winds most of the day on Friday
will shift NW late on Friday, with gusts up to 25 kts.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......MPC