581
FXUS63 KGRB 220830
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
230 AM CST Mon Dec 22 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Light snow to spread north this morning, resulting in a band of
  1 to 2" accumulations centered on the Hwy 29 corridor. Freezing
  drizzle may mix in at times, resulting in slippery travel during
  the morning and evening commutes.

- Above normal temperatures are expected through the work week,
  with highs expected to read above freezing.

&&

.DISCUSSION...
Issued at 154 AM CST Mon Dec 22 2025

Precip chances... Radar returns show light snow over southeast
Minnesota early this morning coincident with the nose of a
developing LLJ and right-rear quad of an upper jet. Snow should
make it to central Wisconsin within the next few hours, spreading
north and east throughout the morning before reaching the Hwy 29
corridor by the Monday morning commute. Pockets of moderate
snowfall (0.5 to 0.75"/hr) will be possible as top-down saturation
occurs, resulting in potential for hazardous/slippery conditions
during travel time. Upper shortwave looks to be fairly weak and
transient, so suspect that amounts within the main band of precip
will total between 1 and 2 inches, locally higher in areas of
focused mid-level FGEN. CAMs latch onto a signal for some
freezing rain mixing in as winds take on a more southerly
component and a push of WAA warms the near-surface layer, though
remain pessimistic in this sense. Warm nose looks to be extremely
shallow, only reaching +1 or 2 degrees. Dry air also begins to
work its way into the column by late morning, so suspect that
freezing drizzle would be the more likely scenario. This being
said, any freezing precip falling on top of fresh snow may create
some slippery spots on roads. In addition, new CAM development
shows a secondary round of freezing drizzle developing from west
to east later this evening and overnight across our southern two
tiers of counties due to isentropic lift along the leading edge of
stronger WAA. Low-level lift thus increases, though any
precipitation processes look to remain below 5k ft where better
saturation is. Have hand-drawn in PoPs accordingly.

Ensemble cluster analysis shows a signal for more widespread
precip arriving toward the end of the week, though there are still
significant timing/location issues within the synoptic pattern.
This being said, p-type issues would likely arise as warmer air
dominates most of the CONUS. Will continue to monitor in the
coming days, especially with potential impacts to post-holiday
travel in question.

Temperatures... Consistent signal for above average temperatures
over at least the next week as height rises and periods of
southerly flow usher in a +20C anomalous airmass at 850 mb. Highs
will read above freezing for most through the end of the work
week, with some locations across central Wisconsin and the Fox
Valley even flirting with 40 degrees. Above freezing dewpoints
will accompany the warmer air, which, when paired with the
possibility of rain, could result in the development of widespread
fog/low clouds on Christmas.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1050 PM CST Sun Dec 21 2025

VFR conditions into the overnight with thickening mid clouds from
the southwest. Strengthening winds just above the surface will
create LLWS at all the TAF sites through Monday morning.

A round of snow will move north into central WI late tonight and
continue spreading north through late Monday morning, before shifting
east and ending. Cigs will drop to MVFR as the snow moves through,
with IFR over central and north-central WI. Expect a 2-4hr period
of light to moderate snow with IFR visibility for all sites except
RHI and MTW. Once the snow ends, a mix of MVFR to low-end VFR cigs
will linger over the region.

For ground operations snow accumulations of around 1" are expected
at most terminals Monday morning, however, a narrow swath of 1-3"
is possible along and north of a CWA to GRB line.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......JLA

NWS GRB Office Area Forecast Discussion