NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 261100
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
500 AM CST Wed Nov 26 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A Winter Storm Warning remains in effect for north-central
  Wisconsin through 6 am Thursday morning. Heavy snow of 6 to 12
  inches is expected, with locally higher amounts in excess of 18
  inches possible in the northwest corner of Vilas County.

- A Winter Weather Advisory has been issued for the rest of north-
  central and northeast Wisconsin through late this afternoon due
  to accumulating snow of 1 to 4 inches and blowing and drifting
  snow.

- A Wind Advisory has been issued for central, east-central, and
  far northeast Wisconsin today. Strong northwest winds gusting 35
  to 45 mph, locally up to 50 mph, will develop today. This will
  lead to blowing and drifting snow in the winter headline areas
  and difficult driving conditions for high profile vehicles
  across the entire area.

- Confidence is increasing for accumulating snow on Saturday.
  There is an increasing potential (60-80% chance) for greater
  than 3 inches of snow over eastern Wisconsin, which may impact
  post-holiday travel.

&&

.DISCUSSION...
Issued at 337 AM CST Wed Nov 26 2025

The latest RAP analysis indicates a potent mid-level cyclone
moving into western Wisconsin this morning, with an associated
surface low tracking east-northeast near Iron Mountain. A warm
conveyor belt of precipitation is currently lifting northeast
across north-central Wisconsin to Door County, while a dry slot is
punching into central and east-central Wisconsin. This dry slot
is aiding in mixing down gusty southwest winds, which are helping
to scour out earlier foggy conditions. A robust comma head with
convective elements is positioned over western Wisconsin and will
pivot across the forecast area today, serving as the primary focus
for wintry precipitation and strong winds in the near term.

Summary of headline changes:

1. Delayed the start time of the Winter Weather Advisory over
central Wisconsin until 6 am today due to the presence of the dry
slot and temperatures in the middle 30s.

2. Added the Wind Advisory to the remaining areas where a Winter
Weather Advisory had already been issued. While strong winds are
typically embedded in a Winter Weather Advisory, felt that there
will be more awareness of the strong winds if a Wind Advisory was
in effect.

3. The Wind Advisory timing was matched up with the Winter Weather
Advisory in all counties except for Door, where the Wind Advisory
will go until 6 am Thu.

Today through next Tuesday:

The primary near-term concern remains the winter storm conditions
unfolding across north-central Wisconsin. As the comma head of
the cyclone sweeps east today, precipitation will transition to
all snow across the north in a regime of strong cold advection.
Thermodynamic profiles are becoming increasingly favorable for
heavy snowfall rates, particularly over Vilas County, where lake
enhancement will augment synoptic forcing. Delta-Ts are forecast
to increase from 14C to 18C through the day, with equilibrium
levels rising to around 10 kft. Combined with a deep dendritic
growth layer, this setup supports efficient snow production. The
heaviest snowfall is expected in the snowbelt of Vilas County,
where there is a high probability (60-90%) of exceeding 12 inches
of accumulation. While forecast snow totals have lowered slightly
for Oneida, Forest, and Florence counties, the potential for 6
inches or more remains high enough (50-90%) to maintain the
Winter Storm Warning. Travel in these areas will be very difficult
to impossible due to the combination of heavy snow and
significant blowing and drifting.

Wind impacts will be significant across the entire forecast area
today and tonight. Strong subsidence in the wake of the departing
low, coupled with intense cold advection, will promote deep mixing
of momentum to the surface. Northwest winds will increase rapidly
this morning, coinciding with the passage of the comma head. Wind
gusts in excess of 45 mph appear likely (50-80% chance) across
most of the region. Probabilities for gusts exceeding 50 mph are
30-50% over central and east-central Wisconsin, as well as the
Door Peninsula, where a few gusts to 55 mph are possible late this
afternoon. A Wind Advisory has been issued to cover these
threats. Even in areas under winter weather headlines, the Wind
Advisory has been added to emphasize the non-precipitation hazard,
particularly for high-profile vehicles on north-south oriented
roadways.

For Thanksgiving Day, the weather will remain cold and blustery
but generally quieter than Wednesday. Lake effect snow showers
will persist across the snowbelt of Vilas County, potentially
adding another 1 to 2 inches of accumulation, while scattered
flurries may develop elsewhere due to steep low-level lapse rates
in cyclonic flow. High temperatures will range from the middle 20s
to lower 30s. Drier air arriving Thursday night will bring a
gradual clearing trend and diminishing lake effect activity,
though clouds will quickly return Friday ahead of the Saturday
system.

Looking ahead to the holiday weekend, attention turns to a system
forecast to impact the region on Saturday. An amplifying long-
wave trough over the center of the continent will send a
strengthening shortwave across the region, supporting the
development of a surface low. Guidance has trended significantly
stronger with this system over the past 24 hours, shifting the
track to a path favorable for heavy snow across eastern Wisconsin.
Probabilities for snowfall exceeding 3 inches have notably
increased, now reaching 60-80% for the Fox Valley and Lakeshore
areas. This presents a concern for post-Thanksgiving travel.
Anyone with travel plans on Saturday should monitor the forecast
closely as confidence in accumulating snow continues to grow.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 459 AM CST Wed Nov 26 2025

A strong cyclone will pass across the region today, leading to
widespread precipitation, a mix of LIFR/IFR/MVFR conditions, and
strong winds.

The rain snow line is progressing across central and north-central
Wisconsin early this morning, and generally stretches from
Rhinelander to Marshfield. The precipitation will change to all
snow further east by 18z today. Once the precip switches to snow
in all areas, very strong and gusty northwest winds will develop
this morning. Wind gusts 35-45 kts are expected across the entire
area into early Wednesday evening, before wind gusts diminish
slightly to 25 to 35 kts by late Wednesday evening. The snow and
gusty winds will result in blowing snow and reduced visibility to
at least IFR at times for all terminals on Wednesday. The worst
prevailing conditions in terms of snowfall and reduced visibility
will be over north- central WI, including RHI, where snow amounts
of 3 to 5 inches are expected through late Wednesday afternoon.

Conditions will steadily improve for all areas on Wednesday
evening as the system exits the region. Ceilings will generally
range from MVFR to VFR tonight as the snow becomes confined to
areas north of RHI.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 6 AM CST Thursday for WIZ005.

Winter Storm Warning until 6 PM CST this evening for WIZ010>012.

Wind Advisory from 9 AM this morning to 6 PM CST this evening
for WIZ013-020-021-031-037>040-045-048>050-073-074.

Winter Weather Advisory from 9 AM this morning to 6 PM CST this
evening for WIZ013-020>022-031-037>040-045-048>050-073-074.

Wind Advisory until 6 PM CST this evening for WIZ018-019-030-035-
036.

Winter Weather Advisory until 6 PM CST this evening for WIZ018-
019-030-035-036.

Wind Advisory from 9 AM this morning to 6 AM CST Thursday for
WIZ022.
&&

$$

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