691
FXUS63 KGRB 090331
AFDGRB

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

Updated aviation portion for 06Z TAF issuance

.UPDATE...
Issued at 816 PM CST Sun Feb 8 2026

After some expansion of the low stratus late in the afternoon into
early evening, some erosion has taken place in the last hour,
including into the Fox Valley. This is likely the result of
decreasing instability and a slight veering of the low level wins
over Lake Michigan. Have therefore removed a slight chance of snow
and flurries in the upslope areas of far NE WI.

Elsewhere, a cloud layer between 3500-4500 ft is showing little
signs of movement and overcast skies can be expected for the rest
of the night.

&&

.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 06Z TAF Issuance
Issued at 931 PM CST Sun Feb 8 2026

Onshore southeast flow continues to pull moisture off Lake Michigan,
maintaining areas of MVFR ceilings from the lakeshore into north-
central WI. These low clouds, with bases between 1500-2500 ft
AGL, are showing signs of erosion over the past 1-2 hours, which
could lead to an earlier return to VFR than forecast at KGRB,
KATW, and KMTW. For now, will maintain the bkn020 ceilings at KGRB
and KMTW, but predictability is low regarding the departure of the
MVFR ceilings.

Further west at KAUW, KCWA, and KRHI, the MVFR ceilings are going
in and out across the terminals. Remained pessimistic at KRHI and
went SCT at KAUW/KCWA. Still think the MVFR ceilings will depart
overnight as low level flow veers to the southwest.

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 north of a KAUW to KGRB
line between 21-00z. Southeast winds will become gusty on Monday,
with gusts of 15-20 kts possible.

After 00z Tue, focus for a wintry mix will generally remain north
of a KRHI to KSUE line. Cooling temperatures aloft will lead to
more snow mixing in after 03z at RHI. Probabilities of MVFR to
IFR flight conditions will increase around this time.

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.
&&

$$

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

NWS GRB Office Area Forecast Discussion