291
FXUS63 KGRB 101148
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
648 AM CDT Tue Mar 10 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Hazardous travel possible tonight into Wednesday morning as
  accumulating snow arrives across the north late this afternoon.
  A wintry mix including freezing rain possible across portions of
  central and east- central Wisconsin overnight (40-50% chance of
  a light glaze).

- Second wintry system will be possible Thursday into Thursday
  night, bringing snow again to the northwoods and a mix of
  rain/snow across portions of central to east-central Wisconsin.

- A third round of winter weather over the upcoming weekend could
  bring additional accumulating snowfall to the entire forecast
  area.

&&

.DISCUSSION...
Issued at 310 AM CDT Tue Mar 10 2026

A fairly active weather week lies ahead for the region as fast
moving and progressive upper level flow brings several fast moving
system through the region. As a result, several rounds of
rain/snow lie in store over the next week.

The first round of precipitation will be around the far north
early this morning, ahead of the "true" first wintry system.
Transient fgen accompanied by some low level moisture will result
in some brief light snow, mainly for north-central near the Upper
Peninsula border. Impacts with this initial wave are expected to
be minimal.

The first system will arrive later in the day as warm air
advection increases from a system to our south. Accumulating
snowfall is expect from the evening hours through the overnight
into Wednesday morning, especially across northern Wisconsin.
Confidence in at least 4 inches of snow now stands around 60-80%
for areas between Rhinelander and Iron Mountain, so a Winter
Weather Advisory is in effect for these region. Further south, the
lingering low level warm air will bring the potential for mixed
precipitation as colder air returns ahead of the upper trough
after midnight through early Wednesday morning. Freezing drizzle
appears likely, with probabilistic guidance bringing potential up
to 80% chance for a light glaze for areas between Wausau/Stevens
Point to Green Bay. However, this does not take into consideration
the record warmth from Monday and highs in the 40s today, which
could keep road surfaces warm enough to mitigate greater impacts.
Still, given the colder signal in the most recent guidance and the
tendency for raised surfaces such as bridges to cool faster,
would watch for some travel impacts Wednesday morning, especially
for commuters along Highway 29. Any mixed precipitation will push
out of the region fairly quickly by the mid to late morning as
the colder air arrives with the upper trough and any lingering
precipitation switches to snow. Only minor accumulations follow
before dry conditions return Wednesday evening.

The second system will look relatively similar, with a late day
arrival Thursday evening, crossing the region overnight, and a
quick exit by early Friday afternoon. This second system will also
be accompanied by a push of warmer air, but this time the signal
for a warmer layer aloft is absent, so precipitation types are
much more likely to remain rain/snow. Confidence is increasing
that this system will bring impactful snow however, with around
50-60% chance of exceeding six inches in the current forecast
cycle. The details on the where and when however remain more
variable as the rain/snow line remains uncertain at this time.

Finally, all eyes turn to the weekend system which may end up
being the highest impact system of the three in the forecast.
Winter Storm Severity Index and probabilistic guidance both point
towards a high impact system, with some potential to exceed 6 and
possibly even 10 inches of snowfall (~20% in portions of the
area). That said, keep in mind that the upper wave expected to
produce this system is just making landfall in Alaska today,
so the track and therefore the who gets what still remains highly
variable. Still, given the high end potential with this system,
its worth keeping an eye on the forecast.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 648 AM CDT Tue Mar 10 2026

Good flying conditions are expected across most TAF sites for the
morning period. Scattered light snow showers may then work their
way into the region during the morning period, which will impact
RHI throughout the afternoon with on and off snow and possibly
rain chances. Precipitation then becomes more widespread in the
late afternoon and evening, with lowering ceilings for all TAF
sites, likely getting into MVFR and then IFR by the late evening
to early overnight. Precipitation will be mainly snow for the far
north including RHI, but a mix of freezing rain, sleet, and ice
pellets may mix in at times during the overnight period as
surface temperatures dip below freezing but warmer temps stay
aloft. Overall, ice accumulations will be low, but a light glaze
will still impact aviation operations for a period during the
overnight hours. Confidence in the southern extent of mixed
precipitation was not clear, so kept to a PROB30 for the ATW TAF
this issuance. Precipitation will switch to all snow by late
Wednesday morning.

Winds will be gusty today across many TAF sites across central and
east-central Wisconsin, with periodic gusts up to 25 knots as
well. The gusts will likely remain as high as 20 knots overnight
and into Wednesday morning as wind direction shifts from the
northeast to the northwest. With gusts mixing to the surface,
removed LLWS for now, but if winds do decouple overnight, expect
LLWS to return to the TAF for the early Wednesday morning period.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 4 PM this afternoon to 1 PM CDT
Wednesday for WIZ005-010>013-018-019.
&&

$$

DISCUSSION.....Uhlmann
AVIATION.......Uhlmann

NWS GRB Office Area Forecast Discussion