Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 041820

Area Forecast Discussion
National Weather Service Green Bay WI
1220 PM CST Sun Dec 4 2016

Updated aviation portion for 18Z TAF issuance

Issued at 1016 AM CST Sun Dec 4 2016

Light to moderate snowfall continues to overspread the area ahead
of a shortwave trough now moving into the northern Mississippi
Valley. Some of the coldest cloud tops are moving northeast from
eastern Iowa and heading for northeast Wisconsin. Based on these
trends and short-term guidance, have expanded the winter weather
advisory a row of counties north into north-central Wisconsin and
also Door County, where 3 to 4 inches of accumulations are now
expected. Some uncertainty in snowfall amounts remains along the
lakeshore, mostly due to a developing south wind and its impact on
temperatures this afternoon. Temps aloft look cold enough for
mainly snow, except right near the lakeshore. So think Kewaunee
and Door counties will fair well with accumulations. Also changed
the ending time of the advisory until 03z tonight for far
northeast Wisconsin, since another inch of accumulations will be
possible after 00z.

.SHORT TERM...Today...Tonight...and Monday
Issued at 300 AM CST Sun Dec 4 2016

Light snow was moving into western Wisconsin as of 08Z, ahead of
a mid level trough that was over the Plains. As the trough moves
into the Great Lakes Region today, snow timing and amounts are
the main forecast concerns.

The 00Z GRB sounding revealed plenty of dry air with the exception
the 900mb-850mb layer that was just below a strong inversion. The
DVN and MPX soundings were not as dry. Moisture is expected to
deepen enough overnight to possibly bring a dusting of snow to
central Wisconsin by 12Z. Snow will spread across the forecast
area during the morning and continue this afternoon.

Think that totals should be in the 2 to 4 inch range across central
and parts of east central Wisconsin today, with the highest totals
in central Wisconsin. It should be slightly warmer farther east,
with highs above freezing, which could melt some of the snow
resulting in lower totals. Even warmer air along Lake Michigan
shoreline should keep snow amounts even lower there.

There could be up to an inch of accumulation during the evening
before this system departs, generally in the far northeast part of
the area. Dry conditions should prevail after midnight and through
Monday. Clouds will keep temperatures from dropping much during
the night.

.LONG TERM...Monday Night Through Saturday
Issued at 300 AM CST Sun Dec 4 2016

A low pressure system over the northern Midwest will strengthen
as it drifts northeast into Canada toward Hudson Bay. The low will
pull cold air south from Canada into Wisconsin. Temperatures will
drop to at or below normal for this time of year starting
Wednesday and continuing through next weekend. Normal high
temperatures are around 30 in the Fox River Valley region and mid
to upper 20s for northern Wisconsin. Normal lows range from around
15 degrees in the Fox Valley to around 10 degrees in northern

For the work week, there is a slight chance for light snow across
the area on Tuesday, but moisture will be limited and snowfall
accumulation should generally be under an inch. Starting
Wednesday, moisture from Lake Superior will fuel periodic lake
effect snows over far northern Wisconsin for several days starting

.AVIATION...for 18Z TAF Issuance
Issued at 1220 PM CST Sun Dec 4 2016

IFR conditions and snow expected through the early
evening hours, with gradual improvement to MVFR overnight. Most
airports will have at least a slushy accumulation of snow on runways,
taxiways and ramps. There is some uncertainty about how much clearing
of low clouds there will be Monday. Looks like the areas east of
an Iron Mountain to Wisconsin Rapids line have the best chance to
see some clearing.

Winter Weather Advisory until 6 PM CST this evening FOR

Winter Weather Advisory until 9 PM CST this evening FOR WIZ022-


AVIATION.......MPC is the U.S. government's official web portal to all federal, state and local government web resources and services.