NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 181001
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
401 AM CST Sun Jan 18 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Clipper system brings around an inch of powdery snow this
  afternoon into tonight, immediately followed by strong gusty
  winds gusting 30-45 mph which will result in areas of blowing
  and drifting snow regionwide late tonight through Monday
  morning.

- Winter Weather Advisories issued for Vilas County due to lake
  effect snow along with blowing and drifting snow, and also for
  Door County mainly due to blowing and drifting snow off the Bay
  of Green Bay. Whiteout conditions are possible at times on Door
  County.

- Cold Weather Advisory in effect for the entire area late tonight
  through noon on Monday, with additional cold weather headlines
  likely into Tuesday.

&&

.DISCUSSION...
Issued at 400 AM CST Sun Jan 18 2026

Active winter pattern continues except now we are going to
introduce strong winds and associated hazards into the picture as
arctic air arrives late tonight into Monday.

Snow into Tonight...
Trough lingering over northeast WI continues to support light snow
and flurries this morning over northeast WI. Eventually forcing
with this shifts east, allowing the snow to end briefly by mid
morning. Attention is already on next clipper system currently
spreading snow from Manitoba to the northern Plains. As the parent
clipper low translates southeast, expect light snow to spread into
central WI by early afternoon, steadily shifting across the region
into this evening. Snow will be light and powdery and not add up
to more than an 1.5", with best chances of amounts that high in
central WI.

Lake effect snow will increase this evening over Vilas County
which will increase the amounts there. For a while tonight,
forecast soundings look favorable for at least moderate snow
(>0.5"/hr) with lake EQL up to 10kft and DGZ at least initially
within cloud bearing layer. Late tonight as core of colder air
begins to move in, DGZ will lower to the sfc, so SLRs will being
to lower as well as the snow begins to take on more of a sandy
type consistency. This is not great for piling up accumulations,
but it is very efficient at reducing visibilities when paired with
any wind of note, which certainly arrives late tonight. Issued a
Winter Weather Advisory for Vilas to cover both the snow accums
and lower visibility in open areas. More on the winds below.

Winds Increase Resulting in Areas of Blowing/Drifting Snow...
Strong push of cold air advection, deep mixing results in good
portion of 30-40kt winds mixing to the sfc late tonight. For a
baseline, expect wind gusts across most of the area of 30-40 mph
late tonight through mid morning Monday (4am through 10am) as the
arctic air first arrives. Winds will be stronger over Door County
(30-50% chance of 45+ mph). Expect solid gales on the Bay and Lake
Michigan and a Gale Warning has been issued. These strong winds
following on the heels of the widespread powdery snow that will be
on the ground raises concern we'll see blowing and drifting snow
even where snow will have recently ended. At the least, open areas
that have seen blowing and drifting in the past will likely have
issues. Given all the fluffy snow on the ground though, this event
could be more widespread than that given the winds/gusts we are
expecting. Tough to gauge that right now though, especially in the
more forested areas of northern WI. Could eventually see a Winter
Weather Advisory or SPS issued to cover the hazard, though this
may be a nowcast type of situation based on upstream observations.

More confident there will be issues downstream of the Bay of
Green Bay in Door County given the snow that falls today and the
loose powdery snow that is sitting on the now mainly frozen bay.
Potential there for whiteout conditions at times. Issued a Winter
Weather Advisory for Door County to cover the potential for very
low visibility in blowing and drifting snow. Similar setup could
occur downwind of Lake Winnebago on a more localized scale. Strong
winds begin to settle down late Monday morning into Monday
afternoon.

Bitter Cold Wind Chills...
Arctic air arriving late tonight with temps by Monday morning
dropping below zero central and north-central WI and falling into
the lower single digits above zero eastward to the Fox Valley and
even the lakeshore. Wind chills drop to around 30 below, with
15 to 25 below zero for all but far northeast WI and Door County.
Have expanded the Cold Weather Advisories to all remaining areas,
except Door County. Though the headlines end at noon on Monday,
only a brief reprieve is expected Monday afternoon, before wind
chills drop to criteria again Monday night into Tuesday morning.
Long story short, the cold weather headlines will either be
extended or followed up by another headline. The cold really does
not ease up until later Tuesday as wind chills rise to zero to 10
below.

Rest of the week...
Active winter weather persists. A clipper system with more
QPF/snow expected for the region Tuesday night into Wednesday.
Current indications dig this more over southern WI, but this
system has been bouncing back and forth. More snow could occur
late this week ahead of a very sharp mid-level trough dropping
across the western Great Lakes. ECMWF is very frigid, compared to
what occurs early this week, showing a 850mb temp over northern WI
of -35C! Note there is a *lot* of spread in the ensemble blend
(LREF) from 25th to 75th percentile for 850mb temps (as seen by
variance in EC versus GFS MOS guidance temps for Friday at GRB
with -6F from the EC but +16 from the GFS). Current forecast is
currently colder for the weekend, but just know this part of the
forecast could change significantly in the coming days given the
spread and lack of model run-to-run consistency.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1056 PM CST Sat Jan 17 2026

A mix of MVFR/VFR conditions were noted across the area late this
evening as a mid level shortwave and attendant surface trough
produced light snow and flurries. These conditions are expected to
last through the overnight hours as the shortwave and trough track
through the area. Snowfall accumulations will be light, with at
best a few tenths of an inch of light fluffy snow.

Quiet weather is then expected for early Sunday morning, with the
next round of light snow moving in from the west late Sunday
morning and lasting through Sunday evening. This activity is
expected to drop conditions to IFR/LIFR at times.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM this evening to 9 AM CST
Monday for WIZ005.

Cold Weather Advisory from 3 AM to noon CST Monday for WIZ005-
010>013-018>021-030-031-035>040-045-048>050-073-074.

Winter Weather Advisory from 3 AM to noon CST Monday for WIZ022.
&&

$$

DISCUSSION.....JLA
AVIATION.......Kurimski