376
FXUS63 KGRB 170442
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1042 PM CST Tue Dec 16 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Chance of freezing drizzle across far northern Wisconsin
  tonight. Locally hazardous travel conditions possible.

- Mix of rain, freezing rain and snow expected Wednesday night
  into early Thursday, then rain changing to snow Thursday
  afternoon and evening. Flash freeze possible late Thursday
  afternoon and evening. Travel concerns from late Wedenesday
  night through Thursday night.

- Light snow possible Friday night into Saturday morning.

- Periodic windy conditions and a chance of gales on Lake
  Michigan through the rest of the work week.

&&

.DISCUSSION...
Issued at 339 PM CST Tue Dec 16 2025

Tonight and Wednesday...south to southwest winds have helped to
boost temperatures into the 30s and lower 40s this afternoon. The
mild readings will be short-lived, as another cold front
(currently over MN) brings a push of colder air to the region
tonight. RH timesections show low-level moisture increasing in the
wake of the front, and satellite confirms abundant low clouds
over NE ND and NW MN. The low-level moisture looks like it may
deepen just enough for patchy drizzle/freezing drizzle over far
northern WI tonight, though there doesn`t appear to be much lift
in the saturated layer, so it should be light. Low clouds should
break up from west to east late tonight, leading to plenty of
sunshine across the forecast area on Wednesday. Temperatures will
not be nearly as warm as today, with highs only expected to reach
the upper 20s and lower 30s.

Mid-week Mixed Precipitation System...A strong low pressure
system will track through the Lake Superior/Upper MI area late
Wednesday night into Thursday. Strong WAA develops ahead of the
system as a 50 to 60 knot low-level jet develops, but moisture
will initially be lacking during the evening. Deeper saturation
occurs overnight, leading to a mix of mainly rain/freezing rain.
The freezing rain will largely depend on whether road temperatures
are below freezing or not. Soil temperatures at 2 inches are all
in the 30-33 degree range right now, and air temperatures are
expected to be in the 20s Wednesday evening, so road temperatures
should be around the freezing mark. Added sub-freezing road
temperature grids in AWIPS to force the inclusion of freezing
rain Wednesday night. The threat of freezing rain should end
Thursday morning as road and surface temperatures warm. A cold
frontal passage will cause rain to change to snow from west to
east Thursday afternoon and evening. In addition, surface
temperatures will quickly drop below freezing from west to east
during the late afternoon and evening, causing any wet and
untreated roads to become icy in spots. All of this points to
potential for hazardous travel from late Wednesday night through
Thursday night. Ice accumulations late Wednesday night should be
under 0.05 inch. Snow accumulation will amount to an inch or less
in most areas, through totals as high as 2 to 4 inches are
possible in Vilas County due to the influence of lake-effect
Thursday afternoon and night.

End of the week...
A clipper system passes through the region Friday night into early
Saturday, bringing a round of light snow to much of the forecast
area, with highest amounts expected across the north.

Winds...
Several periods of gusty winds are expected through the week, as a
series of clipper systems and associated cold fronts move through.
Not real condfident with gale potential for any of the WAA events
on the front side of these systems, though borderline gales could
occur during the post-frontal CAA periods. Right now, gales look
most likely on Friday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1042 PM CST Tue Dec 16 2025

Late this evening, a cold front was moving across northwest
Wisconsin. It remains on track to push across the region overnight.
Relatively strong winds exist in the lowest 3 km above ground
level ahead of and behind the front. Therefore, low level wind
shear conditions are expected at all terminals through
approximately 06z-09z. After a break, high confidence that low
level wind shear will return on Wednesday evening.

MVFR ceilings (1400-2800 ft) developed over north- central WI
(RHI) on time (around 03z). These lower clouds will continue to
spread southeast across the rest of the region, likely persisting
into early Wednesday morning before departing.

Skies are expected to clear on Wednesday morning, returning the
entire area to VFR conditions. Cloud bases will lower again on
Wednesday evening, but should remain VFR through the end of the
taf period.

Gusty winds will veer to the northwest following the cold front`s
passage overnight. The gustiness should subside some on Wednesday
morning. As wind directions become southerly on Wednesday
evening, gusts from 20 to 25 kts will be possible by the end of
the taf period.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion