Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241208

Area Forecast Discussion
National Weather Service Green Bay WI
608 AM CST Sat Feb 24 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Sunday
Issued at 350 AM CST Sat Feb 24 2018

A vigorous upper system will produce some wide swings
of weather tonight and Sunday as it moves quickly from the northern
Plains into the Great Lakes.

The negatively tilted upper trough induces rapid cyclogenesis as
a surface low is forecast to deepen more than 12 mb between 00z
and 12z Sunday as it moves from Missouri to Upper Michigan. If
this were the east coast, it would be called a bomb. We don`t have
the warm Gulf Stream nearby to produce a huge snowstorm, but there
is enough moisture for six inches of snow across far northcentral
Wisconsin and lesser amounts of snow mixed with sleet, freezing
rain or rain elsewhere. The precipitation will end quickly Sunday
morning, followed by strong west winds creating gales on Lake Michigan
and some blowing and drifting snow across the north.

Dense fog across parts of central and northcentral Wisconsin
should dissipate by 15z today. Otherwise we will have increasing
middle and high clouds with temperatures several degrees above
normal. Lows tonight will be just 3 to 5 degrees below todays
highs due to cloud cover, wind and precipitation. Skies should
clear Sunday with gusty winds and near normal temperatures.

.LONG TERM...Sunday Night Through Friday
Issued at 350 AM CST Sat Feb 24 2018

Flow aloft is expected to be zonal or southwest for most of this
part of the forecast and temperatures should be above normal
through the end of the work week.

There is little chance for any precipitation through at least
Tuesday as a surface high passes south of Wisconsin. Light snow
is possible in central and eastern Wisconsin Tuesday night north
of a stationary front that is forecast to be southeast of the area.

The next chance for significant precipitation is Wednesday night
ahead of the next short wave and surface low that will approach
the region from the Plains. Snow chances are expected to spread
across the remainder of the area early Thursday morning before
warmer air changes snow to rain across most of the area during the
day. A change back to all snow should occur Thursday evening as
the back edge of the precipitation approaches. There is still a
chance for snow in northern and eastern Wisconsin later Thursday
night and Friday in cyclonic flow behind the departing system. The
00Z GFS/ECMWF/Canadian all showed significant differences in their
handling of this system. Hopefully the models begin to converge
on a solution fairly soon.

.AVIATION...for 12Z TAF Issuance
Issued at 608 AM CST Sat Feb 24 2018

Areas of dense fog and low clouds will produce LIFR
conditions over parts of central and northcentral Wisconsin
through around 15z. Mostly VFR conditions expected otherwise

A winter storm will move quickly across the region tonight, and
bring mostly snow west of a Wausau to Iron Mountain line, and a
mixture of snow, sleet and freezing rain further east. Mostly rain
is expected near the lake and bay. Low level wind shear is
expected for awhile tonight.

The storm will exit early Sunday with improving weather conditions
but with strong west surface winds of 20 to 30 knots. some
blowing and drifting snow is possible in the north Sunday.

Winter Weather Advisory from 9 PM this evening to 6 AM CST
Sunday for WIZ011>013-018>021-030-031-035>037.

Winter Storm Warning from 9 PM this evening to 6 AM CST Sunday
for WIZ005-010.


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