317
FXUS63 KGRB 101143
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
543 AM CST Wed Dec 10 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Snow exits around sunrise this morning. Gusty northerly winds
  this morning from the Fox Valley to the lakeshore with freshly
  fallen snow may result in patchy blowing and drifting snow in
  open areas.

- Much colder temperatures by this weekend with daytime highs 20
  to 30 degrees below normal. Bitter cold wind chills as low as 15
  below to 30 below zero are likely. Cold Weather Advisories will
  be needed, with even a potential for Extreme Cold Warnings in
  some areas.

- Periodic light snow chances late this week into early next week
  with the highest chances on Friday (30-50%) as arctic cold front
  arrives.

&&

.DISCUSSION...
Issued at 136 AM CST Wed Dec 10 2025

Short Term...Today...Tonight...and Thursday

Off the top, no changes to the current Winter Storm Warnings and
Winter Weather Advisories at this time. Will continue to evaluate
radar and observation trends early this morning to see if any
changes are needed.

Snow ending/gusty winds this morning...Snow within deformation
axis and weak TROWAL of potent clipper shortwave and surface low
is tracking across central and east-central WI early this morning.
Expected lull in snow has occurred parts of central WI, but additional
snow is poised to move back across in the next 1-2 hours. As the
low over southern WI heads toward southern Lake Michigan, and
eventually over lower MI, expect the snow to diminish toward
sunrise. As colder air works in from the north with sufficient
moisture, could see some lake enhanced snow try to hang on closer
to the Bay of Green Bay and near the immediate Lake Michigan
shoreline even after the primary area of snow departs. Even here
though, expect lingering snow to end by 14z-15z/8-9am. Additional
snowfall overnight through the rest of the morning will be a few
inches at most, heaviest over east- central WI (Fox Valley to the
lakeshore) where pivoting deformation axis resides the longest.
Peak snowfall rates from here on out will be up to 0.5" per hour
instead of the 1+" per hour rates we had last evening.

NE winds will be strongest over east-central WI this morning
(peaking through 10 am), with gusts of 30-35 mph based on forecast
soundings and HREF/NBM probabilities. These winds will lead to
some blowing and drifting of the freshly fallen snow in open
areas, but the wetter character of the snow (SLRs 10-14:1) will cut
down on blowing snow/reduced visibility compared to what would occur
if the snow was more powdery (SLRs 20:1 or higher).

Theme of the rest of the day will be colder temps gradually settling
in along with abundant stratocu as northwest winds cross the open
waters of Lake Superior. Some breaks in the clouds will occur east-
central with downsloping flow, but overall a mostly cloudy later
morning into the afternoon. Afternoon temps will drop into the
teens far north and fall into the mid 20s Fox Valley to the
lakeshore. Clouds will clear out tonight as high pressure ridge
over the plains arrives. Temps dropping into the single digits
above and below zero could lead to low stratus forming late over
central and north-central WI. Seems to be just enough sfc wind to
prohibit freezing fog, but where it gets the coldest it is not out
of the question.

Mixed sun and clouds on Thursday will give way to increasing
clouds by afternoon. Chilly with highs many areas staying below
20. Too much dry air below the mid clouds for any snow to form,
though a few flurries could occur over central WI toward sunset
as mid-level fgen and increasing lift moves into western WI ahead
of the next clipper system crossing the central plains.

Long Term...Thursday Night Through Tuesday

The arrival of bitterly cold arctic air this weekend is the primary
concern for the long term forecast. Additionally, multiple rounds of
light snow are possible late this week through the first half of
next week.

Bitter Cold This Weekend...Global ensembles continue to be in good
agreement that much colder temperatures will arrive this weekend
behind a cold frontal passage Friday. 01Z NBM means have lows
ranging from near 0F along Lake Michigan to the negative teens below
zero across central WI Saturday and Sunday mornings. Wind chills may
fall into the negative 15F to negative 30F degree range both
mornings as a steady NW breezy persists within the CAA regime. Cold
weather headlines will likely be needed at times this weekend. The
extent of cloud cover will be a key factor is just how cold some
locations get each morning. Current guidance suggests Saturday
morning may be partly to mostly cloudy while Sunday morning skies
may be more clear.

Snow Chances Friday through the Middle of Next Week...A mid-level
short-wave ahead of a cold front is progged to develop across the
eastern Dakotas Thursday and track southeast across Iowa Friday.
This setup would put southwest and parts of central WI Wisconsin
in a favorable location for banded snowfall. South and west of HWY
10 the 01Z NBM shows 30-50% chances for greater than 1" of snow
Friday. Snow chance further north are tied more to the cold front
which would limit total accumulations in those region.

Mean LREF upper-level flow pattern keeps the region within the
northwest flow through the weekend and into the early part of next
week. With this on and off chance for light snow will be possible
with any short-waves that pass through the flow. There is some
indication that the western CONUS ridge begins to break down and
shift east during the middle of next week. This would allow for
temperatures to moderate toward normal with highs getting back into
the 30s by next Wednesday.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 543 AM CST Wed Dec 10 2025

Swath of snow from central to east-central WI will taper off through
14z. Vsby during heaviest snow will be as low as LIFR with IFR cigs.
Expect vsby to quickly improve as the snow ends. Cigs will generally
remain MVFR through the day, before scattering out this evening.
Low clouds are possible late tonight over central WI as nighttime
cooling to around zero sets up sharp low-level inversion. Though
not in the forecast at this time, it is possible that shallow
freezing fog could occur.

North winds will increase this morning, with gusts over 25 kts in
east-central WI and locally near 35 kts near the Lake Michigan
shore much of the day. LLWS will occur this morning as well at
all the sites. Winds become light tonight as high pressure
arrives.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST early this morning for
WIZ018>021.

Winter Weather Advisory until 9 AM CST this morning for WIZ022-
073-074.

Winter Storm Warning until 6 AM CST early this morning for
WIZ030-031-035>037-045.

Winter Storm Warning until 9 AM CST this morning for WIZ038>040-
048>050.
&&

$$

DISCUSSION.....JLA/GK
AVIATION.......JLA