618
FXUS63 KGRB 222352
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
552 PM CST Sat Nov 22 2025

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Mild with no significant precipitation expected until late
  Monday afternoon or evening.

- A pattern change is expected in the middle of next week, with
  colder and blustery conditions, along with possible gale force
  gusts on the bay and lake. Snow accumulation is likely over
  northern Wisconsin Wednesday into Thursday.

&&

.DISCUSSION...
Issued at 203 PM CST Sat Nov 22 2025

Highest impact portion of forecast in form of accumulating snow
and strong/gusty winds does not arrive until late Tuesday night
and Wednesday.

Until then, a few sprinkles this afternoon tied to warm air
advection ahead of cold front moving across MN will give way to
tranquil late fall weather tonight through the rest of the
weekend. Southern stream system currently over Baja California
will lift northeast, but unravel as it does so. Even so, expect
widespread light rain to move across the region Monday afternoon
through Monday night, tapering off on Tuesday. Strongest moisture
advection is farther south, so probabilities for rainfall over
0.25 inch are low.

As this lead system exits, attention will be on stronger, more
dynamic northern stream trough and associated sfc low that will be
diving east-southeast across the northern Plains late Tuesday.
Rain with warm air advection ahead of the low spreads over the
western Great Lakes region Tuesday evening, then as the low
deepens over Lake Superior, cold air will surge in across WI,
changing any mixed precip to snow rather quickly. Thermal profiles,
critical thicknesses and forecast 2m temps, point to minimal risk
of any freezing rain/sleet, which is also supported by ptype probs
from NBM.

Primary impacts in terms of snow, wind or both slated to occur on
Wednesday, which is the busy travel day the day before Thanksgiving.
Differences in sharpness of trough will dictate extent of deformation
and/or TROWAL wraparound snow into especially northern WI. Flatter
and less negatively tilted trough will not favor as much heavy snow,
while sharper features would. This will be in combination to
favorable NW wind trajectories providing lake enhanced snow into
north-central WI. Ensembles bear this out, with low-end snow
amounts still mainly in the advisory range while higher-end
scenarios (75th-90th percentile) reach into warning criteria. Snow
amounts will be considerably less away from north-central WI, but
even minor accumulations could occur from central to northeast
WI. Gusty northwest winds over 30 mph will likely lead to blowing
and drifting snow over north-central WI. And, even where snow
accumulations are minor, the gusty winds (gale gusts developing
on the bay and lake) with even light snow will lead to potential
for reduced visibility. Early, but the models are even showing
snow squall potential in parts of the area as the colder air
arrives, likely buoyed by steeper low- level lapse rates. Overall
the already busy travel day is looking like it could be impacted
by wintry conditions. Hard to get too much into the details at
this point, but will continue to mention in the HWO. Those with
travel plans need to keep up to date with the latest forecasts as
we get closer.

Beyond Thursday, pattern remains active into next weekend. Lake
effect will continue through Friday over north-central WI as
conditions remain cool and blustery all areas. Another bout of
wintry precipitation could then occur sometime next weekend.
Critical thicknesses and sfc temps would point ptype remaining
mainly snow over our area and pattern suggests some accumulation
would be possible.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 552 PM CST Sat Nov 22 2025

Main concern for the TAF period will be the passage of a cold
front, which will bring in a period of LLWS for much of the
overnight period at all TAF sites. Sky cover is expected to clear
out again tonight before the next round of mid level clouds push
into the region Sunday afternoon.

&&

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

&&

$$

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