744
FXUS63 KGRB 051110
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
510 AM CST Wed Nov 5 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Chance of rain across eastern WI Thursday night. Chance of rain
  and snow over northern WI on Friday.

- The first accumulating snow of the season may occur for some
  this weekend, particularly across north-central WI.

- Near normal temps through Friday, then colder this weekend into
  early next week.

&&

.DISCUSSION...
Issued at 210 AM CST Wed Nov 5 2025

Active pattern continues. Temps will be slightly above normal
through Friday, then it turns colder this weekend with mainly lake
enhanced snow into early next week. Cold does not lock in though,
as indications are that it will warm up again heading into mid
November.

Precipitation/Ptype: Weak low pressure system will cross northern
WI early this morning, bringing scattered light rain to northern
WI into this morning. Looks too warm in boundary layer to support
any mention of snow mixing in, just light rain.

Stronger shortwave just coming ashore in the Pacific Northwest
this morning, heads east and leads to cyclogenesis over the
northern Plains late Thursday. This 995mb low then tracks across
northern WI/Upper Michigan Thursday night, before pushing a cold
front across the area on Friday. Continue to see model differences
in extent of saturation which mainly impacts how far west in our
area will see steady light rain. Blend of GFS, ECMWF, Canadian
ensembles (LREF) suggest most of the area sees at least some rain,
but probabilities of QPF higher than 0.10 inch are less than 50%
even over far eastern WI where overall chances for rain are greatest.
Scattered light rain/snow showers develop behind the cold front
Friday into Friday night north-central. Even with sufficiently
cold air aloft (H85 temps -3c falling to around -8c Fri night),
overall weak cyclonic low-level flow and lower inversions point
to generally light intensity lake effect rain/snow showers
north-central WI.

Farther south trend that started showing up in the weekend system
last night continues, suggesting main swath of accumulating snow
with clipper low will stay to the south, maybe even mainly south
WI. Hint that there could be slight expansion of what would be
mainly light snow/flurries on Saturday night over northern and
eastern WI on fringe of the system as northern stream shortwave
trough digs in, providing a boost in forcing. Though that would
bring first flakes for some, appears real chance for accumulating
snow will be over north-central WI Saturday night through Sunday
night with increasing lake enhanced snow. Increased pops, but
given the setup with cyclonic northerly flow and lake EQLs rising
above 10kft, they will likely increase further as we get closer to
this weekend. LREF/NBM probabilities show 40-60% of seeing 2+
inches of snow Saturday night through Sunday night, but with
favorable setup think a more realistic idea for snow totals is
offered up by 90th percentile from NBM (v5.0) which shows 3-5" in
the favored snowbelts of northern Vilas County (north of
Manitowish Waters and Boulder Junction), tailing off to 1-3" for
the rest of Vilas County into Oneida County, north of Rhinelander.
At least a couple inches could also occur locally in northern
Door County toward Washington Island, with Sunday being the main
time frame to see the snow there. One last spot to watch for some
lake effect snow accums will be along the immediate shoreline of
Lake Michigan. If a more north-northeast low-level flow occurs as
ECMWF points to, a couple inches of snow could occur. If the flow
is more NNW like the GFS favors, not so much. Elsewhere on
Sunday, spotty snow showers and flurries may occur at times. Lake
effect snow showers and flurries gradually end Monday into Monday
night as winds back southwest.

Winds...Once the low pressure and cold front pass to our north
early this morning, winds shift northwest and will gust up to 30
mph. Next period of gusty winds will be from the south closer to
the bay and Lake Michigan Thursday night as gusts could reach
20-30 mph. Northwest winds on Friday behind the front still don`t
look as gusty. Strongest winds this weekend will occur from the
northwest in the colder air on Sunday.

Temperatures...Near to slightly above normal temps prevail through
Friday, then bottom drops out this weekend. Saturday serves as
transition day with readings near 40F at the lakeshore, while
rest of area only reaches mid to upper 30s. Highs on Sunday and
Monday will be cooler, with all areas staying in the 30s, potentially
below freezing north. Highs rebound some Tuesday, but will remain
below normal. Nights will be chilly as all areas see lows in the
20s starting Saturday night. Coldest nights will be Sunday night
and Monday night, with mins in the teens central and north-central
WI.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 510 AM CST Wed Nov 5 2025

A few showers or sprinkles will graze far north this morning (even
north of RHI), but no vsby reductions are expected. Otherwise,
VFR cigs this morning (035-060) will scatter out this afternoon.
Cigs will briefly fall to MVFR during the morning at CWA/AUW/RHI.
Skies become clear by this evening, before mid and high clouds
increase again late tonight.

Northwest winds will gust 20 to 30 knots today. Winds will diminish
by sunset, remaining light from the west/southwest the rest of the
night.

&&

.MARINE...
Issued at 210 AM CST Wed Nov 5 2025

Active marine pattern continues. South winds early today will
build waves to 5 feet for Lake Michigan nearshore waters. Winds
shift northwest this morning and will gust to 25-30 kts through
this evening in all areas, including the bay. Small Craft Advisory
is in effect through this evening. A brief break later tonight
into Thursday morning, then another period of small craft advisory
conditions will occur late Thursday into Thursday night. A few
gale gusts may occur, but mostly this will be over the open
waters. The strong southerly winds will build waves to 7 to 10
feet for much of the Lake Michigan nearshore waters Thursday night
into Friday morning.

&&

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

&&

$$

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