Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121216

Area Forecast Discussion
National Weather Service Green Bay WI
616 AM CST Tue Dec 12 2017

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 343 AM CST Tue Dec 12 2017

Snow showers and flurries should end by midday as a surface ridge moves
across the area. Gusty northwest winds across the Door Peninsula will
also diminish by midday. Temperatures today will be around ten degrees
below normal. At least some clearing is expected this afternoon before
middle and high clouds return tonight ahead of the next clipper system.

The clipper system looks like is has more potential to produce significant
snow than the last couple of systems. This one has a coupled upper jet,
is moving slower, has better low level warm advection and convergence
and should have a better trajectory for winds coming across Lake Michigan.
The models all suggest that 3 to 5 inches of snow are likely over much
of the area Wednesday, with some potential for six inches or more south
and east of Green Bay. Winter Weather headlines will likely be
issued later today.

In addition to the snow, gusty northeast winds will produce some blowing
and drifting snow in the Lakeshore and Fox Valley Wednesday afternoon
and evening.

.LONG TERM...Wednesday Night Through Monday
Issued at 343 AM CST Tue Dec 12 2017

500mb ridge across western North America with a resulting downstream
trough across eastern North America will will dominate the weather
pattern into the weekend. The pattern should gradually flatten next
week. This pattern will bring periodic chances of light snow with
clipper systems dropping southeast out of Canada. Behind the
departing systems, lake effect snow showers are possible at times
across far northern Wisconsin. Temperatures should run at or below
into the weekend, then temperatures may return to or slightly
above normal early next week.

The first clipper system will bring a chance of light snow or
flurries to portions of northeast Wisconsin Wednesday evening.
Any additional accumulation should be less than an inch. Across
the north, the chances of lake effect snow showers will linger
into Thursday morning. Another weak upper level disturbance will
bring a chance of light snow or flurries to north-central and
central Wisconsin later Thursday afternoon, then across northeast
Wisconsin Thursday night. The chances of lake effect snow showers
increase through the night Thursday night and continue into

Attention turns to another clipper system Friday into Saturday.
Low confidence in timing and location of this system based on the
different model solutions. Otherwise, night time lows should stay
above zero across the north during the period based on expected
wind and cloud cover. If we should get a night with light winds
and clear skies, temperatures may need be lowered at least 10
degrees. A clipper system passing to the north of the area early
next week should usher in milder air across the region Monday.

.AVIATION...for 12Z TAF Issuance
Issued at 616 AM CST Tue Dec 12 2017

Ceilings between 2500 and 3500 ft expected through midday along
with some brief snow showers or flurries. Clearing is expected
this afternoon and evening but it will not last very long, as
middle and high clouds will increase later tonight as a Clipper
system approaches from the northwest. Snow and IFR conditions
will arrive in central and northcentral Wisconsin late tonight and
over the rest of the region Wednesday. Snow accumulations of 2 to
5 inches are expected in most places with higher amounts possible
near Lake Michigan.

Wind Advisory until 10 AM CST this morning for WIZ022.


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