394
FXUS63 KGRB 031158
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
558 AM CST Sat Jan 3 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A dusting to half an inch of snow today for most locations.
  Probabilities of more than 1" are ~5-10%.

- A more impactful system will bring snow and freezing drizzle
  Sunday afternoon through early Monday morning, leading to some
  slippery travel Sunday evening and possibly into the Monday
  morning commute time.

- Warmer temperatures are expected next week, which will bring
  precipitation type challenges to the systems coming through
  Tuesday and again late in the week.

&&

.DISCUSSION...
Issued at 423 AM CST Sat Jan 3 2026

High pressure is building in from the west early this morning
keeping the low levels dry, but higher up a mid-level short wave
and upper jet energy are aiding in advancing mid and high clouds
through the area. Some weak returns showing up on radar across
central WI, but far too dry for anything to reach the ground.

As the morning progresses, the dry wedge of air gains saturation,
and with the continued lift from the upper level features, some
light snow or flurries are expected to develop. Forecast remains
very similar to previous runs, with a dusting to half an inch
expected for most locations. Probabilities for greater than 1" of
snow today are ~5-10% or less. Still, even a little snow can cause
some slick spots on roads.

Surface high pressure reestablishes this evening leading to
clearing skies overnight into Sunday morning, aside from far
north-central WI where NW winds will keep some lake induced clouds
around. High pressure quickly departs Sunday afternoon allowing
the next system to approach.

Overall, minimal changes to the forecast for Sunday afternoon into
Monday morning. Clipper is still on track to approach the area
Sunday evening, and quickly depart to the east Monday morning.
Strong LL warm advection ahead of this system will aid in bringing
in moisture and lift to initiate precipitation, along with
additional support from a mid-level shortwave and LFQ of upper
jet. Timing may be an hour or two earlier than previous forecasts,
but generally expect to start seeing snow in central WI between
~2-4PM, and reaching eastern WI ~4-7PM. Forecast soundings and
cross sections show the period of deep saturation and strong lift
is relatively brief, lasting about 3-6 hours. Therefore, expect
most of the snow to occur between ~00-06Z/Mon, maybe a little
earlier in central WI. After 06Z, start to see moisture erode in
the DGZ, although there remains a couple hours where saturation is
right up to about -10C, just beneath the layer where you`d expect
to see ice crystals for snow formation. So, there is some
uncertainty for how long snow will persist past 06Z, and if/how
long a period of freezing drizzle may occur after the main snow.
Continued to include light freezing drizzle in the forecast
overnight until about 12Z/Mon, and a little longer in eastern WI
as the system departs. This should mainly fall on fresh snow, and
not lead to many additional impacts.

Total snow from this even is similar to the previous forecast.
The probabilities for 1" of snow have a large range across the
forecast area, from 30-95% from SW to NE, lowest across Wood and
Waushara counties, and highest near the U.P. border. The potential
for 4" of snow is greatest north of a Rhinelander to Sturgeon
Bay, where probabilities are 30-50%. An Advisory may eventually be
needed, especially for northern/northeast WI. Slippery and
hazardous travel is expected late Sunday afternoon and overnight,
and possibly into the Monday morning commute time, especially
across the east.

After Monday, there remain several opportunities for precip as the
pattern remains active. Most notably on Tuesday/Tuesday night and
Friday/Saturday. P-types will be an issue as warmer air arrives
and highs surge into the 30s during the days, but fall into the
20s at night. Additionally, the ground/roads may still be cold
following the recent stretch of cold weather, which could
produce additional road impacts with any ptype.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 558 AM CST Sat Jan 3 2026

Starting to see dips to MVFR across north-central WI this morning
as light snow arrives, creating lowering vsbys and cigs. Light
snow will continue to spread across the area this morning, and end
from west to east in the ~18-21Z time window. Expect flight
conditions to fall to MVFR at most locations as the snow moves
through, with temporary vsby drops to IFR not out of the question
at the central and north-central WI TAF sites (KRHI, KAUW, KCWA).

Improvements this evening and overnight as skies clear for most,
although lake clouds will continue at KRHI.

Winds will be out of the WNW throughout the TAF period and
generally 10 kts or less.

Another round of snow is expected Sunday afternoon and overnight
which will lower flight categories.

&&

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

&&

$$

DISCUSSION.....KLJ
AVIATION.......KLJ

NWS GRB Office Area Forecast Discussion