104
FXUS63 KGRB 011105
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
505 AM CST Mon Dec 1 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Light snow will move across the area this afternoon and evening.
  Accumulations of a half inch to an inch are expected, which
  could lead to scattered slippery stretches on roadways for the
  evening commute.

- An arctic front will bring another chance of light snow Tuesday
  night into Wednesday, followed by the coldest air of the season so
  far.

- Hazardous wind chills of 10 to 20 below zero are forecast for
  Thursday morning west of the Lake Michigan shoreline.

&&

.DISCUSSION...
Issued at 227 AM CST Mon Dec 1 2025

Short Term...Today...Tonight...and Tuesday

The latest RAP analysis and satellite/radar imagery show mid-level
height rises taking place across the western Great Lakes between
shortwave energy over the eastern Great Lakes and energy over the
northern Plains to the Rockies. Broad warm advection is taking
place across the central Plains with high clouds streaming into
Iowa and southern Minnesota. Over Wisconsin, a large area of
clouds remains stubborn over the northwest half of the state
associated with thermal troughing at 850mb. Within that cloud
mass, scattered flurries are occurring, which has held up
temperatures in the Northwoods early this morning. As the various
shortwaves move across the Plains and into the center of the
country, light snow chances are the focus of the forecast through
tonight.

Precipitation Chances: Shortwave energy currently over the Northern
Plains will dig southeast into the northern Mississippi Valley this
afternoon and the western Great Lakes tonight. Moisture from the
central Plains will stream northeast ahead of the shortwave over the
course of the day. With the mid and high clouds moving overhead, it
is difficult to envision the low stratus mixing out over north-
central WI, so a mention of flurries was kept through the morning
hours.

With deepening saturation, a chance of light snow will move into
central WI in the early to mid afternoon hours, before proceeding
northeast into northeast WI from mid to late afternoon. It appears
central to northeast WI will have a 6 to 9 hour window for light
snow. Forecast soundings indicate ascent looks rather weak and
located above the dendritic growth zone. Therefore, anticipate lower
snow ratios than initialized with the NBM and minor accumulations,
perhaps a half inch to an inch by the end of this evening, highest
over east-central WI. Scattered slippery spots could develop on
roads, particularly for the evening commute, but it should not
cause significant impacts. Most of the light snow activity should
taper off or exit east by late tonight.

Cloud Trends and Temperatures: Confidence is rather low regarding
how long low clouds will stick around after the snow ends late
tonight into Tuesday morning. Current thinking is that low clouds
will hold tough into Tuesday over north-central WI, but northeast
parts of the state could see some clearing. High temperatures
today will range from the mid teens to lower 20s. Similar highs
are expected Tuesday, ranging from the lower  to middle 20s.

Long Term...Tuesday Night Through Sunday

The main focus of the long term forecast revolves around the passage
of an arctic front mid-week, bringing accumulating light snow followed
by the coldest airmass of the season.

Snow Chances Tuesday Night/Wednesday: Additional shortwave energy
moving across central Canada and the northern Plains will push an
arctic front across the region late Tuesday night into Wednesday. A
period of deep saturation along the front will bring the next chance
of light snow to the region. Snow chances generally range from 30 to
50 percent. QPF values have been increased slightly based on
numerical model output rather than the national blend of models to
account for the forcing. Most areas could see a half inch of
accumulation, but isolated amounts up to 1 inch will be possible.

Temperatures and Wind Chills: Behind this arctic front, the coldest
air of the season will arrive. High temperatures on Thursday will
struggle to reach the single digits and lower teens. Lows below zero
are expected on Wednesday night away from the immediate
lakeshore. Combined with steady west to northwest winds, wind
chills are forecast to range from 10 below to 20 below zero
Wednesday night into Thursday morning west of the lakeshore and
bayshore.

Extended Outlook: Temperatures will moderate slightly heading into
the weekend, returning to the 20s. Additional light snow chances
will arrive from Thursday night through the weekend as clipper-type
systems traverse the flow. Confidence regarding significant or
impactful snow remains low during this period, though some guidance
produces a relatively stronger system for next weekend.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 504 AM CST Mon Dec 1 2025

A mix of VFR/MVFR ceilings were observed across the forecast area,
with the lowest ceilings over the northwest part of the region.
An erosion of the MVFR stratus is slowly occurring over north-
central WI, and there could be a few hour period at RHI where
ceilings turn VFR this morning.

A short- wave trough arrives in the afternoon, resulting in
increasing clouds and eventually some light snow across C/EC WI
after 20z. Flight conditions should drop to MVFR/IFR once the
steadier light snow develops.

After the snow exits by mid to late evening, ceilings should
remain MVFR over central to north-central WI, and may become VFR
over the northeast WI terminals.

Light southwest winds today will become west late tonight.

&&

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

&&

$$

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