Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 112131
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
331 PM CST Mon Dec 11 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Tuesday
Issued at 331 PM CST Mon Dec 11 2017

Forecast concerns in the short term includes precipitation
associated with the departing surface low and mid level trough,
winds behind the departing system, and lake effect snow showers
across northern Wisconsin.

Expect any remaining snow to depart and freezing drizzle will end
by evening. Strong cold advection is forecast to result in lake
effect snow showers in north central Wisconsin tonight through
Tuesday as wind direction becomes more favorable for lake effect.
Blustery conditions are expected tonight with gusts of 25 to 35
mph at most locations. Winds across Door County will be stronger,
with gusts around 45 mph, especially north of Sturgeon Bay.

The combination of cold temperatures and blustery winds will
produce wind chills mainly in the single digits below zero later
tonight through Tuesday. Lows tonight are forecast to be in the
single digits to around 15 degrees. Temperatures on Tuesday are
expected to top out about 5 degrees warmer than tonight`s lows.

.LONG TERM...Tuesday Night Through Monday
Issued at 331 PM CST Mon Dec 11 2017

High amplitude flow with an upper ridge over the western Conus
and the deep cold trough over the eastern states will keep the
forecast area in the cold northwest flow regime for much of the
week.

Lake effect snows will be on the decrease Tuesday evening as a
surface ridge drifts over the area. Overnight lows Tuesday night
may be of the falling early then steady variety as clouds with
the next clipper system approaches the area. Latest height 850 mb
trough appears to be weaker with this system and the trend of the
surface low track is southward.

Progs continue to support this next clipper type system dropping
over the western Great Lakes region from Wednesday into Wednesday
evening. In addition to the timing and tracking of this system, a
more persistent forecast issue lately with these systems is the
mixed precipitation potential due to mid level saturation has been
challenged at times. After coordination with area offices, will
keep the precipitation type all snow for now.

In the wake of this mid week system, more cold air pours into the
area on north to northwest winds Wednesday night into Thursday to
start up lake effect snows across the far north again. A short
wave trough drops over the region Thursday into Friday morning to
possibly enhance the lake effect snows and produce snow showers or
flurries across the rest of the area.

Progs remain consistent with a pattern change to a more zonal
flow starting Friday. Another clipper type system tracking over
Saturday will still be dealing with the lingering cold air mass to
produce mainly snow.

Some moderation of temperatures from below normal normal levels
this week to near normal next weekend and early next week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1157 AM CST Mon Dec 11 2017

Ceilings were IFR and MVFR across the majority of the forecast
area at midday. There was still some light snow in parts of
northern and eastern Wisconsin, along with patchy freezing
drizzle. Precipitation should come to an end across most of the
area as a surface low and mid level trough depart the region.
Expect conditions to become VFR across most of the area later
today into the evening. Winds increase from the northwest and
become gusty, with some gusts in excess of 30 knots, especially in
Door County. Wind direction becomes more favorable for lake
effect snow showers in northern Wisconsin, so there should be
mainly MVFR ceilings there, with some IFR ceilings and
visibilities in snow showers through at least midday on Tuesday.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 8 PM this evening to 10 AM CST Tuesday for
WIZ022.
&&

$$

SHORT TERM.....MG
LONG TERM......TDH
AVIATION.......MG



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