NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 140004
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
604 PM CST Tue Jan 13 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- A brief period of freezing drizzle and snow may accompany a
  frontal passage tonight, leading to locally slippery roads.

- Accumulating lake-effect snow may cause travel concerns in far
  north central Wisconsin tonight into Wednesday.

- Widespread light snow late Thursday afternoon through Friday,
  with additional chances for light snow into the weekend.

- Turning colder tonight, then moderating toward the end of the
  work week. Another reinforcing shot of cold air arrives over
  the weekend.

&&

.DISCUSSION...
Issued at 326 PM CST Tue Jan 13 2026

Fairly quiet weather was observed across the region this
afternoon, with the forecast area situated between a departing
short-wave and another approaching from NE MN. Strong southwest
winds brought very warm air into the region, with highs touching
50 degrees at Waupaca and Oshkosh. Temperatures were stuck in the
middle to upper 30s over the northwest half of the forecast area,
where widespread low clouds were still in place. Looking upstream,
a strong cold front was moving through northern MN and approaching
Duluth. Light mixed precipitation was observed with the front in
the Arrowhead.

The strong cold front will reach northwest part of the forecast
area early this evening and depart the southeast portion during
the early overnight hours. The front will bring northwest winds
gusting to 30 to 35 mph and a couple hour period of light snow and
drizzle/freezing drizzle at any given location. The addition of a
chance of drizzle/freezing drizzle was based on model depiction
of a brief period of shallow saturation with temps above -10 C
(supercooled water droplets instead of ice crystals) and earlier
observations of freezing drizzle in southern Canada. Confidence in
freezing drizzle is on the low side, as it is unknown if this
setup will occur before or after surface temps drop below
freezing. As such, locally slippery road conditions are possible
but not likely. Accumulating lake-effect snow is expected over
north central WI tonight into Wednesday. Wind trajectories are
looking better than they did yesterday, with a favorable NNW
direction, and synoptic enhancement from a potent short-wave will
occur for several hours tonight. However, decided not to
significantly increase snowfall totals due to a strong inversion
setting up around 3500-4000 ft (low equilibrium levels) and a lack
of a deep dendritic growth zone. Will hold accumulations in the 1
to 3 inch range.

A deep upper level trough and clipper low pressure system move
into the area late Thursday afternoon/evening, leading to
widespread light snowfall and some accumulations into Friday. The
upper trough lingers into the weekend, with numerous lake-effect
snow showers over north central WI and scattered snow showers
elsewhere.

Temperatures turn significantly colder starting tonight, then
moderate a bit into the end of the work week. A couple surges of
chilly arctic air arrive over the weekend and early next week.
This will result in sub-zero min temps and wind chills as cold as
10 below to 25 below zero during the late weekend and early part
of the next work week.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 604 PM CST Tue Jan 13 2026

A fast moving cold front will bring some scattered light
precipitation into northern Wisconsin near the beginning of the
TAF period. This should affect primarily RHI but should have
limited impacts to aviation until temperatures drop to around
freezing. At that point, there may be a brief window for freezing
drizzle before switching over to snow. Some light precipitation
will also accompany the front southeastwards, possibly bringing
some light precipitation to GRB, ATW, and MTW but drier air in
this region will limit precipitation. MVFR stratus will be in the
region during this period as well, but should see some scattering
out into a VFR deck Wednesday morning.

Winds will be fairly gusty through the period, with routine gusts
up to 20 to 25 knots overnight and on Wednesday. Stronger winds
will be off the surface but are expected to currently stay around
4-5k feet AGL, so removed the LLWS from the TAF.

&&

.MARINE...
Issued at 326 PM CST Tue Jan 13 2026

Gusty west winds bring small craft conditions through this
evening. A strong cold front moves through later tonight, followed
by northwest gales to 35 to 40 kts, which will last into Wednesday
evening. Even with an offshore wind direction, high waves and
freezing spray will occur, especially toward open water on Lake
Michigan.

&&

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

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......Uhlmann
MARINE.........Kieckbusch