Forecast Discussion for GRB NWS Office
FXUS63 KGRB 262338

Area Forecast Discussion
National Weather Service Green Bay WI
538 PM CST Tue Jan 26 2021

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Wednesday
Issued at 321 PM CST Tue Jan 26 2021

Snow had mostly come to an end across east-central Wisconsin this
afternoon, with some light snow or flurries possible into the
early evening hours across the lakeshore counties. Additional
snowfall accumulations will be negligible as the low continues
moving off to the east. Lake effect snow across the Lake Superior
snowbelt of north-central Wisconsin will continue through the
night with a favorable fetch and delta T values. There could be a
dusting of accumulation tonight, mainly across northwest Vilas

Satellite imagery shows the extensive cloud cover across the
region could develop breaks this evening, which should cause
temperatures to fall to 0 to 5 across north-central Wisconsin,
with lows of 10 to 15 across east- central Wisconsin. The expected
splotchiness of the clearing will mean overnight lows could
plummet with clearing, then shoot up again as clouds track back
over the region. Therefore, wild swings in temperature are
possible tonight with a few locations probably dropping below zero
across north-central and central Wisconsin.

Mid level troughing and northerly winds will continue for
Wednesday as another shortwave brings a fresh deck of clouds
during the morning hours. Drier air advecting in from the west and
a high pressure ridge building across the upper Mississippi Valley
in the afternoon will bring a decrease in clouds by the afternoon,
especially across central and east-central Wisconsin. Clouds will
linger longest across the north, with a continued feed of
moisture from Lake Superior. Highs on Wednesday are only expected
to reach 10 to 15 across north-central Wisconsin, with highs
around 20 across east-central and northeast Wisconsin.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 321 PM CST Tue Jan 26 2021

Quiet winter conditions expected to start the long term, then
attention turns to if/when a system will impact the area this
weekend. Temps will start off below/near normal, then return to
above normal this weekend.

Wednesday night through Friday...a quiet stretch of weather is
expected for the area as surface high pressure over western
Ontario extends into the western Great Lakes. Some early day sun
is possible on Thursday, then clouds look to take over. Wednesday
night look to be cold with mostly clear skies expected in the
evening. Some increase in clouds, along with the potential for fog
could stop the temps from falling overnight. Most spots look to
fall into the -10 to +10 degree range, warmest near Lake
Michigan. Highs on Thursday look to be slightly below normal,
mainly in the teens to lower 20s. Weak WAA and more clouds look to
hold up low temps Thursday night but it will still be a
seasonally cold night. Continued WAA will allows highs to climb
into the 20s on Friday.

Rest of the long term...main weather concern will be if and when
the next system will impact the area. As the surface ridge slides
into eastern Ontario and Quebec, a shortwave will eject out into
the southern Plains. Models fairly consistent with the overall
progression of the shortwave and surface low, tracking into the
Ohio Valley on Sunday. But as was the case with today`s system,
minor differences in track and if/where a heavier band sets up and
where the northern cutoff will occur will be a tricky forecast
endeavor. 12z ECMWF took a jump southward with the system with
the strong surface high winning the tug of war battle, keeping our
area mainly dry. Will see if this was a head fake or a trend. Any
type of lake enhancement looks to be reduced as 850mb temps will
only be around -5C, plus some pretty dry air will be feeding in
from the east. Still too early to add much value, so kept the
blend for PoPs. A lingering trough could keep chances for snow
into Monday. Temps look to be slightly above normal.

.AVIATION...for 00Z TAF Issuance
Issued at 538 PM CST Tue Jan 26 2021

VFR conditions are expected tonight through Wednesday, except for
some MVFR ceilings and snow flurries at times north of a Tomahawk
to Iron Mountain line as lake effect clouds sometimes make it
that far inland from Lake Superior. Surface wind speeds will be
fairly light and the visibility excellent.




SHORT TERM.....Kurimski
LONG TERM......Bersch

NWS GRB Office Area Forecast Discussion