Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 051744

Area Forecast Discussion
National Weather Service Green Bay WI
1144 AM CST Mon Dec 5 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 324 AM CST Mon Dec 5 2016

Spotty light mixed precipitation will continue to depart northeast
of the area early this morning as a short wave trough shifts east
of the area. Noticed a few observations across the north early
this morning reporting light pcpn. Challenge with the forecast
then turns to cloud trends this morning followed with the next
chance of light mixed precipitation tonight into Tuesday. Across
the eastern two thirds of the country, a southern stream short
wave with frontal system will reach the ohio valley into by Tuesday,
but the northern stream system sliding over the northern plains
will affect part of the state through Tuesday.

Clearing line on the heals of the departing system working into
Clark county early this morning, so anticipate some brief clearing
into at least parts of central Wisconsin early today as a weak
ridge slides over. Satellite imagery also shows a large area of
stratus clouds over the eastern areas of Iowa and Minnesota and
southern Wisconsin. What clearing that does occur will likely be
short lived when southerly boundary layer winds developing ahead
of the northern plains system lift the clouds north. waa clouds
will also be on the increase today.

Warming 850 MB temperatures to +2 to +4 C tonight will provide a
mix potential although pcpn amounts and chances will be minimal.
Colder air begins to work into the area late tonight into Tuesday
to turn the pcpn type to light snow from west to east, but the
system is already tracked to the north, so small pops and mainly
over northern Wisconsin. Boundary layer winds also more westerly
Tuesday in the wake of the cold front so Lake Superior LES snows
should stay north through Tuesday.

.LONG TERM...Tuesday Night Through Sunday
Issued at 324 AM CST Mon Dec 5 2016

Surface and 500mb lows are forecast to pass north of Wisconsin
Tuesday night. There will be a slight chance for snow across north
central Wisconsin Tuesday night and Wednesday in moist cyclonic
flow around the departing lows.

Much colder, and below normal, temperatures are expected for
Wednesday, with highs in the 20s across the area. West winds of
10 to 20 mph will bring wind chills down into the teens and single
digits. This begins a stretch of colder weather that will last
into the weekend.

Winds veer as a surface ridge approaches and flow aloft becomes
northwest. This will cause winds to become more favorable for
lake effect in north central Wisconsin, especially Thursday
through Friday when at least a couple of inches of accumulation
can be expected. Totals could be significant but will wait to see
what upcoming model runs show.

Lake effect will wind down Friday night as the surface ridge axis
passes east of the area and winds back, becoming unfavorable. On
Saturday warm advection in return flow is expected to bring a
chance for snow to the area. Have left the initial model blend
alone for the weekend due to the differences in the location of
max QPF among the models.

.AVIATION...for 18Z TAF Issuance
Issued at 1139 AM CST Mon Dec 5 2016

continued mvfr/ifr cigs are expected as warm air pushes low level
clouds into northeast Wisconsin. Cigs should remain low through
the night ahead of an approaching cold front in the Northern
Plains. Some light pcpn is possible tonight before the main front
arrive Tuesday morning, mainly in northern Wisconsin. However,
without much moisture to work with and low confidence, left
drizzle/frz drizzle out of the RHI TAF for now. Will need to watch
for later updates.

Snow showers will break out as the cold front marches through the
area later Tuesday morning through Tuesday afternoon. Not much
pcpn is expected as moisture will continue to be limited, but low
cigs and occasional low vsbys are possible. Eastern WI should
speak out a dry morning before light snow arrives a bit later in
the day.




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