067
FXUS63 KGRB 150426
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1026 PM CST Wed Jan 14 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Light lake-effect snow and blowing snow will cause locally hazardous
  travel through this evening in north-central Wisconsin,
  especially over Vilas County, and also over northern Door
  County.

- There is a 60-90% chance for snowfall accumulations greater than
  2 inches across most of the area from Thursday afternoon through
  Saturday. Snow-covered and slippery travel will occur at times.

- Cold temperatures arrive late in the weekend and early next week,
  with wind chills as cold as 10 below to 30 below zero.

&&

.DISCUSSION...
Issued at 234 PM CST Wed Jan 14 2026

The latest RAP analysis and satellite/radar imagery show a sharp
trough axis moving east over Lake Michigan this afternoon with
arctic high pressure centered over the northern Plains. Subsidence
behind this trough is leading to clearing skies over parts of
central and northeast Wisconsin, while lake-effect snow showers
persist in the snow belt of north-central Wisconsin and northern
Door County. Upstream, the next clipper system is rounding the top
of a strong ridge positioned over western North America,
currently located over the Yukon and Northwest Territories. This
feature is on track to reach the Upper Midwest by late Thursday.

North-northwest wind trajectories ahead of the building surface
high will maintain lake-effect snow showers through tonight.
Equilibrium levels are expected to briefly increase to 6-7 kft
this evening before diminishing as a subsidence inversion lowers.
Additional snow accumulations of up to one inch are possible over
the northwest corner of Vilas County, with a half inch or less
expected elsewhere in the north-central snow belt. Gusty winds
will gradually subside through the night as the high pressure
ridge builds in, likely becoming calm over north-central Wisconsin
by early Thursday morning. Skies will transition from scattered
to broken clouds to clearer conditions, though some lake clouds
may linger near the Lake Michigan shore and near the U.P. border.

High pressure will quickly shift east on Thursday morning as mid
and high clouds increase from west to east ahead of the
approaching clipper. A warm advection regime will move in, with
deep saturation reaching north-central Wisconsin by mid-afternoon
and the Fox Valley by early evening. While initial snow amounts
through late Thursday afternoon will be light, there is a 20-40%
chance of a half inch of accumulation by sunset, which could lead
to some slippery spots for the evening commute over central and
north-central WI. A concern for late Thursday afternoon is that
saturation may struggle to reach the -10C level over central
Wisconsin, potentially leading to a loss of ice crystals and a
brief period of freezing drizzle before the column fully
saturates. Highs on Thursday will remain chilly, ranging from the
middle teens to middle 20s.

The most focused period of snow with this system will occur
Thursday night into Friday morning as the trough axis and a potent
shortwave move through the region. Ensemble means support a
widespread 1 to 3 inches of snow, with a 60-90% probability of
exceeding 2 inches over the entire area. Following the passage of
the shortwave on Friday, the area will remain under broad
cyclonic flow. This will keep light snow and flurries in the
forecast through Saturday, though additional accumulations will be
minor and forcing will be weaker. Embedded shortwaves may provide
brief periods of better ascent, but confidence in the timing and
location of these features remains low at this time range. Most
confident in steady snowfall over north-central WI where lake
effect will enhance the snowfall. Probabilities of 4 inches or
greater have ticked upward from 60 to 80% from Thursday afternoon
through Friday night. Consensus among neighboring offices was to
hold off on winter weather headlines, but the need for an Advisory
will need to be monitored.

Another clipper system is projected to cross the Great Lakes in
the Sunday through Sunday night timeframe. This system will
provide a high probability (80-90% chance) for measurable snow
across the region, though it does not currently appear to be a
steady or heavy snowfall event. The primary story with this second
clipper will be the surge of arctic air in its wake. Temperatures
are forecast to trend significantly colder by Sunday night as
850mb temperatures fall to between 25 and 30 below zero. This will
set the stage for dangerously cold conditions on Monday and
Tuesday, with a need to monitor for wind chill headlines.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1025 PM CST Wed Jan 14 2026

An MVFR stratus deck remains in place across north-central
Wisconsin southwards to central Wisconsin, mainly from winds off
of Lake Superior. As winds decrease overnight and gusts drop off,
clearing should work its way back into these areas with mostly
sunny conditions expected for Thursday morning. Areas further east
have remained clear, with VFR skies for GRB, ATW, and MTW.

Attention then turns to the next wintry system which will swing
in from the west Thursday evening and bring a longer period of
light snowfall and likely MVFR ceilings by the end of the TAF
period. Some IFR ceilings and visibility will be possible once we
get into the overnight period Thursday night into Friday morning.

&&

.MARINE...
Issued at 234 PM CST Wed Jan 14 2026

Forecast soundings and ensemble winds/gusts still on track
showing solid 35-40 kt gale gusts through late this afternoon.
Winds taper to 30-35 kts this evening. Even with an offshore wind
direction, high waves and freezing spray will occur, especially
toward open waters of Lake Michigan.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......Uhlmann
MARINE.........MPC

NWS GRB Office Area Forecast Discussion