NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 171130
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
530 AM CST Wed Dec 17 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Mix of rain, freezing rain and snow expected Wednesday night
  into early Thursday, then rain changing to snow Thursday
  afternoon and evening. Flash freeze possible late Thursday
  afternoon and evening. Travel concerns from late Wednesday
  night through Thursday night.

- Light snow possible Friday night into Saturday morning.

- Periodic windy conditions and a chance of gales on Lake Michigan
  through the rest of the work week.

&&

.DISCUSSION...
Issued at 259 AM CST Wed Dec 17 2025

Main focus of the forecast will be on the upcoming wintry system
set to arrive late tonight into Thursday. Following this, another
round of snow or two will also be in the works for the end of the
week into the weekend as the next clipper arrives.

Active Weather Late Tonight Thru Thursday...
A strong low pressure system will track across the western Great
lakes late tonight through Thursday. Precipitation type remains
the most challenging aspect of the forecast, specifically on the
when/where transition occurs. Initial onset of the system early
Thursday morning will feature a wintry mix with snow giving way to
rain as warmer air intrudes in the mid levels and ice becomes
scarce. Freezing rain potential remains limited mainly by surface
temperatures and how quickly these warm. Suspect that prior road
treatments, strong non-diurnal warming pushing air temps into the
30s, and timing discrepancies for precip onset will largely spare
the Fox Valley and areas eastwards from a freezing rain threat, so
removed these areas for the morning period. However, portions of
central, north- central, and northeastern Wisconsin will still see
a window for freezing precipitation through the mid-morning before
this concern ends. Ice accumulations should stay in the realm of a
couple hundreths which will likely be too minor to pose an
infrastructure concern, but any icing will be a travel concern.
Rain will become the predominant precipitation for the late
morning to early afternoon for all but far northern Wisconsin
before snow works its way in with the colder air. Snow totals
remain around an inch or less for most of the area, except far
northern Wisconsin where totals could get up to a few inches from
both lake enhancement and snow being the more dominant p-type.
Finally, timing on when the coldest air returns Thursday evening
remains uncertain but there is potential for a rapid fall in
temperatures which could produce additional icy spots on untreated
surfaces. This will also be another period of stronger wind gusts
in the region. Ultimately, all of this will make for a period of
hazardous travel, so make sure to be ready for changes in road
conditions especially if traveling very early Thursday or late
Thursday evening.

Next clipper late Friday into Saturday...
Another clipper will cross the Great Lakes region overnight Friday
into Saturday, bringing with it another round of light snowfall.
Amounts will likely be higher in northern Wisconsin but overall
should still remain relatively light.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 530 AM CST Wed Dec 17 2025

Fast moving stratus deck will bring some MVFR ceilings to the
region this mornign but is expected to clear out by the mid
morning hours. Cloud bases then lower again in the late evening
ahead of a wintry system for the overnight hours.

Attention then turns to wintry system that arrives overnight into
Thursday, mainly after 00Z. At initial onset, some brief light
mixed precipitation is possible including freezing drizzle/rain.
This should switch to rain relatively early Thursday morning.
Strong winds aloft will accompany the active weather, with 40-50
knot gusts only a couple thousand feet off the surface, so LLWS is
in the TAF as well. Wind gusts may mix to the surface at times
during this period as well, so included a mention of gusts up to
20 to 25 knots. Ceilings will likely become IFR by mid to late
morning on Thursday.

&&

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

&&

$$

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