Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 082056
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
256 PM CST Fri Dec 8 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Saturday
Issued at 255 PM CST Fri Dec 8 2017

Vigorous clipper system dropping southeast from Manitoba will
produce light to moderate snow over the region tonight, with
moderate to possibly heavy snow across the eastern counties where
there should be enhancement of the snow from the lake and bay.

There isn`t an incredible amount of synoptic scale moisture
available, yet the models forecast significant vertical motion and
suitably cold temperatures through the part of the atmosphere that
are conducive to producing large snowflakes. So we think that
will be enough to produce 1 to 3 inches of snow in most places.

Southwest winds blowing over the bay should enhance the snowfall over
the Door peninsula this evening, and then northeast winds blowing over
the lake and bay will enhance the snow near the lakeshore and
perhaps the Fox Valley late tonight as the surface system moves
over the lake. The additional snow should produce totals of 2 to 4
inches over most of the Lakeshore counties, Fox Valley as well as
the southern parts of Oconto and Marinette counties. 3 to 5
inches or more should fall in Door county. Blowing and drifting
snow is possible Saturday morning, especially east of highway 41.

.LONG TERM...Saturday Night Through Friday
Issued at 255 PM CST Fri Dec 8 2017

Active cold northwest upper flow will dominate through next week
with a series of clippers and continued below normal temperatures.
Timing these clippers and tracks along with resulting impacts
will be the primary challenge.

Weak ridging through early Saturday evening will be followed with
a weak short wave trough late Saturday night into Sunday. Progs
not generating much snow but do expect at least some flurries with
a weak mid level trough. Reinforcing shot of cold air and northwest
winds will aid with lake effect snows across the far north into
Sunday.

After another weak ridge of high pressure slides over later
Sunday into Sunday evening before another clipper system
approaches from the northwest. ECMWF and GFS show some agreement
with the surface low tracking southwest of the area and putting
the southwest half or third of the forecast area into the
1 to 3 inches of snow range. Highest amounts over central
Wisconsin.

Pattern does not change much after that as timing of these fast
moving systems becomes increasingly more challenging. The upper
pattern may become more zonal for a time later next week which
could allow a more moderating temperature trend for a few days.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1135 AM CST Fri Dec 8 2017

Parts of northeast Wisconsin may improve to lower end VFR cigs
this afternoon for a time, otheriwse mainly MVFR cigs will linger
this afternoon. Conditions to deterioate to IFR conditions
tonight as a clipper system drops into the state. As the system
departs Saturday morning, conditions to improve over inland areas,
but lake effect snow showers across far north central Wisconsin
and along lake michgian will continue to produce IFR or lower end
MVFR conditions for saturday morningnorningms fss.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM this evening to 6 AM CST
Saturday for WIZ038-039-048-049-073-074.

Winter Weather Advisory from 6 PM this evening to 9 AM CST
Saturday for WIZ022-040-050.
&&

$$

SHORT TERM.....RDM
LONG TERM......TDH
AVIATION.......TDH



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