866
FXUS63 KGRB 081145
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
545 AM CST Sat Nov 8 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Most locations will have potential to see their first snowflakes
  of the season this weekend.

- Accumulating lake effect snow expected tonight across far
  north- central Wisconsin. Several inches of snowfall
  accumulation possible in Vilas County.

- Much colder temperatures expected during the day Sunday and
  Monday.

- Conditions will be hazardous to small craft on the Bay and Lake
  at times over the next week.

&&

.DISCUSSION...
Issued at 346 AM CST Sat Nov 8 2025

A deep upper trough will be the main driver for our wintry
weather and colder temperatures over the next 48-72 hours here in
northeast Wisconsin, including the first snowflakes for most of
the area.

Precipitation Thru Monday...
A passing clipper system will be the
first chance for precipitation in the forecast, passing south of
our region in the afternoon to evening hours. Although this
largely misses the region, some light precipitation remains
possible across portions of central to east-central Wisconsin on
the northern fringe of the more organized precipitation.

Low level winds will shift to the northwest in the wake of the
clipper`s passage, promoting the start of lake effect snow across
northern Wisconsin this evening. Lake effect will likely continue
overnight and even intensify on Sunday as winds from the surface
to 700mb align into a more north to northwest orientation and a
strong upper shortwave crosses into the region. With Delta-T
values off the lake around 20+ C and a saturated layer between
850-700mb, would expect multiple more organized lake effect bands
to push snow into the western Upper Peninsula and north-central
Wisconsin, including Vilas County. Probabilistic guidance has
caught onto this signal as well, with the probability of
exceeding 2 inches over 80% for northern Vilas County, and
probability of exceeding 4 inches up to 40-50%. As a result,
pushed up snow amounts for Saturday night through Sunday night and
issued a Winter Weather Advisory for Vilas, with the expectation
that the best potential for snow will revolve around the
shortwave`s passage on Sunday. Additionally, although snowfall
totals should still exhibit a sharp gradient across the north,
increased pops into the rest of the area as some light snow
showers will still likely accompany the shortwave, even if impacts
from any flurries will be minimal. Finally, maintained lower
amounts of precipitation for the Door Peninsula as the fetch over
the Bay of Green Bay will likely prove too short to see better
enhancement.

By Monday, the better lake effect will depart the region but some
lingering light showers may yet affect areas through the morning
hours. Additionally, a weak push of warm air advection could bring
 some scattered showers back to the region Monday evening, but the
window will be relatively short and the precipitation is expected
to be low impact.

Temperatures...
The push of the much colder air accompanying the
shortwave will drive down high temperatures for Sunday, with highs
ranging from the upper 20s to lower 30s. Couple with windy
conditions at the surface, wind chill readings will be in the
single digits to low teens in the early morning and evening
Sunday. Temperatures moderate some on Monday, with highs returning
to the 30s for most and a few spots getting back to around 40.

Rest of the Forecast...
General pattern then shows westerly to north-westerly flow through
the rest of the forecast period, which is expected to produce
sporadic lake effect, mainly across the Upper Peninsula. If winds
turn more north or northwesterly at times, some of these showers
could work their way into areas near the UP border at times, but
most of the forecast for next week is dry. Temperatures are
expected to moderate again as well, with highs getting back into
the middle to upper 40s for most by the middle to end of next
week.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 545 AM CST Sat Nov 8 2025

Stratus will be in place across the region this morning, with MVFR
ceilings across portions of northern Wisconsin and VFR staying in
place further downslope across central and east-central Wisconsin.

A snowy system will largely miss the region to the south in the
afternoon and evening, but could still clip portions of east-
central Wisconsin, so made a mention in a PROB30 group for GRB,
ATW, and MTW. Lake effect snow also will affect far northern
Wisconsin tonight, but confidence on impacts to aviation was not
high enough to include mention in the RHI TAF.

Finally, winds will remain relatively light today, but gusts will
pick up fairly quickly on Sunday, especially Sunday afternoon
which could see some gusts up to 20 to 25 knots.

&&

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

$$

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