668
FXUS63 KGRB 082318
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
518 PM CST Sun Feb 8 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- There is a 50 to 80 percent chance of light ice accumulations
  over far northern WI later Monday afternoon and Monday evening,
  followed by a half inch of snow. A Winter Weather Advisory has
  been issued for areas along and north of a line from Rhinelander
  to Mountain to Sturgeon Bay from 3 pm Monday through 3 am
  Tuesday. Hazardous travel conditions are expected.

- A mainly dry and mild period is expected for the rest of the
  week, with above normal temperatures anticipated.

&&

.DISCUSSION...
Issued at 316 PM CST Sun Feb 8 2026

Aside from a few flurries in eastern WI, it has been a dry day.
Low clouds expanded westward across the forecast area, but
failed to fill in over our western tier of counties. The low
clouds limited daytime heating, with highs only reaching the 20s.

Expect mainly dry conditions tonight, but did maintain a 20%
chance of light snow or flurries over far NE WI due to WAA and
upsloping SE winds. Overcast skies and lows in the upper teens and
lower 20s are anticipated.

A dynamic clipper system arrives Monday afternoon and night,
accompanied by a a coupled upper level jet, FGEN, a cold frontal
passage, and short-wave trough. The best dynamics and moisture are
focused over far northern WI, where probabilistic forecasts now
show a 50-80% chance of at least a light glaze of ice, with a
20-40% chance of a tenth of an inch right along the Upper Michigan
border. Most of the ice accumulations are expected to occur
during the late afternoon and evening, when significant warm layer
aloft (+3 to + 5 C) will be in place. There is some concern that
surface temperatures will initially be above freezing, but wet
bulbing should occur as steadier rain arrives. CAA, dynamic
cooling and wet bulbing will quickly erode the warm layer aloft
later in the evening, leading to a changeover to snow. Based on
our latest ice accumulation forecasts, and after coordination with
MQT, have decided to issue a Winter Weather Advisory for areas
along and north of a line from Rhinelander to Mountain to Sturgeon
Bay from 3 pm Monday through 3 am Tuesday. Hazardous travel
appears likely, especially near the Upper Michigan border. Most of
the precipitation should pull out of far NE WI late Monday night,
but developing NW flow and CAA may result in scattered lake-
effect snow showers in far NC WI on Tuesday.

High pressure dominates our weather for the rest of the work
week, with only small precipitation chances expected through next
weekend. Below normal precipitation is anticipated for the
period.

Temperatures will trend above normal through the week, with highs
in the upper 20s and 30s on most days.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 516 PM CST Sun Feb 8 2026

Onshore southeast winds continue to transport moisture off Lake
Michigan, maintaining a broad area of MVFR ceilings across much of
the region late this afternoon. These low clouds, with bases
generally between 1500-2500 ft AGL, are expected to persist
through the overnight hours at KGRB, KATW, and KMTW as low-level
wind trajectories remain nearly stationary.

Further west at KAUW and KCWA, MVFR ceilings will likely hold (or
develop) this evening. As winds veer more southerly overnight,
some erosion of the low stratus is anticipated, potentially
allowing for the return of VFR conditions between 06-08Z.
However, mid and high-level clouds will quickly increase from the
west ahead of an approaching system.

Ceilings will fall (but remain VFR) Monday afternoon as a dynamic
clipper system moves into the area. Chances of mixed
precipitation, including the potential for light freezing rain,
sleet, and snow, is expected to increase at KRHI after 21z.
Southeast winds will become gusty on Monday, with gusts of 15-20
kts possible.

Confidence is medium regarding duration of MVFR ceilings tonight,
but lower regarding the exact timing of the wintry mix on Monday
afternoon, and if impacts will occur at KRHI.

Outlook...The clipper system could bring light icing to areas from
north-central to northern Door Peninsula on Monday night.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 3 PM Monday to 3 AM CST Tuesday for
WIZ005-010>013-021-022-073.
&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion