423
FXUS63 KGRB 041057
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
457 AM CST Tue Nov 4 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Active with chances of mainly rain tonight into Wednesday
  morning, then again Thursday night through Friday.

- Mixed rain/snow or snow expected this weekend. Minor snow
  accumulations may occur late Saturday and Saturday night.

- Slightly above normal temperatures this week, then much cooler
  this weekend.

&&

.DISCUSSION...
Issued at 225 AM CST Tue Nov 4 2025

Currently the pattern is slightly mild and active with zonal
flow, but things could turn more interesting this weekend with
the potential for the first (minor) snow accumulation for parts of
the area.

Precipitation/Ptype: Two quick moving low pressure systems cross
tonight, then again Thursday night into Friday. Not much cold air
for these Pacific sourced systems, so main impacts will be gusty
winds and a brief period of mainly rain tonight into Wednesday
morning, then again Thursday night into Friday. Seems to be just
enough cold air at the tail end of both times of precipitation
for light snow/flurries to mix in over far north-central WI
Wednesday morning, then again on Friday.

The weekend system develops as large scale trough deepens over
the Great Lakes as ridging builds over the western CONUS. Pattern
favors a southward push of cold air into the region with 850mb
temps dropping to around -10c for later in the weekend. Lead
shortwave trough, Alberta clipper type low drops across MN/WI
later Saturday into Saturday night. Rain/snow or just snow occurs
along and northwest of the low track. Latest runs of GFS/ECMWF and
Canadian, along with associated ensembles show a trend farther south,
with main west-east axis of QPF over southern WI. This is the main
uncertainty with this system. NBM is not as shunted south with
axis of higher QPF, so we`ll see how that works out. As it stands
now, NBM probabilities for over 0.5 inch of snow (highest from
6p-12a on Saturday night) range from around 20 percent in the Fox
Valley to 30-40% central to north-central WI. If you push that up
to 2", the probabilities even in the north drop to around 10%. So
though we could see accumulating snow in portions of our area, at
first glance it does not look to be too high of an impact. If
heaviest QPF is farther north though (not favored at this point),
there could be accumulation on roads given the temps would be well
below freezing.

Secondary shortwave trough digging over the area on Sunday and
cold north-northwest flow will lead to lake enhanced snow over
northern WI, with flurries and/or snow showers farther south.

Winds...Winds lighter today than what was seen Sunday/Monday. Once
the low pressure and cold front pass to our north late tonight,
expect gusty northwest winds Wednesday. Gusts on land central to
east-central should reach over 30 mph (60-100% chance), but seeing
35-40 mph is less certain (25-45% chance). Next period of gusty
winds will be from the south closer to the bay and Lake Michigan
as gusts could reach 20-30 mph. Northwest winds on Friday behind
the front don`t look as gusty. Strongest winds this weekend will
occur from the northwest in the colder air on Sunday.

Temperatures...Normal highs are in the mid to upper 40s as we
start off November. Readings today with the Pacific airmass will
certainly be outpacing that, with highs in the 50s, with even
some lower 60s not out of the question central WI to parts of Fox
Valley. After today, northern WI will stay in the 40s for highs
the rest of the week, but we`ll still have 50s elsewhere. Bottom
drops out this weekend though. Saturday serves as transition day
as the low pressure crosses, with lower 40s lingering Fox Valley
to the lakeshore, while rest of area only reaches mid to upper
30s. Highs on Sunday and Monday will be cold, with all areas
staying in the 30s, potentially below freezing north. Even taking
the potential for snow off the table, its a near certainty that
areas that have escaped a freeze to this point over eastern WI
will finally see one late this weekend. Coldest nights will be
Sunday night and Monday night, as readings even in the Fox Valley
to lakeshore will drop into the lower to middle 20s.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 454 AM CST Tue Nov 4 2025

VFR cigs (BKN-OVC 100-200) are expected at all terminals today
with cigs lowering to 060-090 tonight ahead of a quick moving low
pressure system. Winds overall will be lighter than the last
couple days, but gusts to 15 kts could still occur tonight at MTW
closer to the stronger/gusty southerly winds on Lake Michigan.

Light rain or sprinkles may occur over northern WI tonight as the
sfc low moves across. No reductions to visibility are expected.
MVFR cigs develop late tonight at RHI once the low pressure
system crosses the area and winds turn to the northwest. Northwest
winds with gusts to 30 kts will occur on Wednesday at all terminals.

&&

.MARINE...
Issued at 225 AM CST Tue Nov 4 2025

We`re into November so not that surprising the marine pattern has
turned quite active. As one Small Craft Advisory drops off early
this morning, another Small Craft Advisory will be issued late
tonight through early Wednesday evening. Initially south winds
will become gusty tonight with waves building to around 4 feet
south of Algoma. Then all areas will see gusty northwest winds
begin around daybreak on Wednesday, lasting through early
Wednesday evening. Gusts in all areas, including the bay, could
reach 30 kts. A brief break Wednesday night into Thursday morning,
then another period of small craft advisory conditions will occur
late Thursday into Thursday night. Southerly winds will result in
waves building to over 10 feet for much of the Lake Michigan nearshore
waters.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......JLA
MARINE.........JLA