256
FXUS63 KGRB 211709
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1109 AM CST Sun Dec 21 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Next round of light snow arrives late tonight into Monday. Any
  lingering precipitation may see a brief wintry mix during the
  afternoon hours.

- Below normal temps today, then above normal readings for most of
  the work week.

&&

.DISCUSSION...
Issued at 248 AM CST Sun Dec 21 2025

The synoptic pattern will become more zonal across the Great Lakes
this week, which will keep larger airmass exchanges out of the
area through Christmas. As a result, high temperatures will be
fairly similar once we get into the work week and precipitation
chances will become more scarce.

The coolest day in the forecast will be today, with highs largely
in the upper teens to middle twenties across the area. Skies are
expected to stay clear much of the day, but some cloud cover will
start to move in from the south overnight as warm air advection
increases ahead of the only notable precipitation in the forecast.

Warm air advection and the arrival of an upper jet late tonight
into Monday morning will bring some scattered precipitation back
to the forecast. Soundings at onset appear cold enough to keep
precipitation largely in the form of snow through the mid to late
morning. As we get into the afternoon however, precipitation may
become more mixed as dry air intrudes aloft and ice becomes
scarce. Depending on surface temperatures, this may allow for a
period of freezing drizzle. That said, the NAM remains the outlier
with this solution at this time, with other models wither
remaining cold enough to stay as snow or ending precipitation
completely. Still, this period may bear monitoring as the freezing
drizzle potential will be Monday afternoon which will likely be a
travel day for some and the end of the work day for others. Snow
totals are light due to the fast moving and low moisture content
of this system, again bringing around an inch or less for most of
the area. Overall, would expect impacts to be low, unless the
freezing drizzle scenario begins to become more prominent.

Behind this, conditions largely stagnate for our area. High
temperatures each day will be largely in the 30s in the afternoon.
This may prove to be sufficient melting to remove a lot of the
snow pack across portions of central and east-central Wisconsin by
Christmas Day. A couple of brief chances of precipitation will be
in the area towards the end of the week, but overall amounts are
currently expected to be light.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1109 AM CST Sun Dec 21 2025

VFR flying conditions will continue through the rest of today.
Visible satellite shows scattered mid-level (4-5kft) moving across
northern WI and eastern MN this morning. Expect those clouds to
steam over the region this afternoon, but produce little aviation
impacts. Tonight strengthening winds just above the surface will
create LLWS at all the TAF sites through Monday morning.

A round of snow will spread north into central WI early Monday
morning and continue spreading north through the TAF period. Expect
flying conditions to deteriorate as IFR/low end MVFR cigs spread in
with the snow. Reductions to MVFR/IFR vsbys is also expected within
the heaviest snow. Have framed out the timing of the heaviest
periods of snow with TEMPO groups at all TAF sites. For ground
operations snow accumulations of around 1" are expected at most
terminals, however, a narrow swath of 1-3" is possible north of a
AUW to SUE line.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion