Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 062030
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
230 PM CST Tue Dec 6 2016

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Wednesday
Issued at 230 PM CST Tue Dec 6 2016

Main forecast issues are in the early part of the short term.
This afternoon`s satellite images showed a deep upper level
trough nearly stationary and continuing to spin over the Western
Great Lakes region. Closer to the surface, a cold front ahead of
the main low pressure system kicked off an area of precipitation
this morning that slowly pushed eastward this afternoon.
Forecasting for this features timing and intensity as well as
precip type has been tricky. Models have been too warm at the
surface as dynamic cool has allowed for low level temperatures to
quickly drop ahead of the precip, so mainly snow has fallen so
far. In addition, models have been too quick to progress the area
of precip westward. While the precip has begun to encounter drier
air in eastern Wisconsin and scour out slightly, given the trends
so far in the forecast and the robust forcing associated with this
feature, increased precip chances this afternoon. Also changed
precip over to snow faster this evening. Wouldnt be surprised if
all snow fell across the Fox Valley before mixing with rain along
the lakeshore.

Once the precip exits the area this evening, the weather should
quiet down for tonight and Wednesday. Flurries and isolated light
snow showers are still possible overnight and Wednesday as colder
air filters into the area, however not much in the way of precip
is expected. Much colder air has already begun to filter into the
state behind the cold front. Temperatures overnight will continue
to drop and then wont rebound much on Wednesday. In addition,
brisk west winds are expected behind the front tonight through
Wednesday, which will result in wind chillS in the single digits
to lower teens. This isnt abnormal for this time of the year,
however it will be a significant change to the weather we have had
in place over NE WI the past few weeks.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 230 PM CST Tue Dec 6 2016

A return to colder weather, lake effect snow in Vilas
county Thursday and Thursday night, and a possible weekend snowstorm
are the main challenges for this forecast period.

Colder air will arrive Wednesday night and Thursday as a sharp
upper trough drops south across the Great Lakes region, and a big
arctic high builds in from Canada and the northern Plains States.
Snow showers and flurries are expected Wednesday night and
Thursday but significant snow should be limited to Vilas county
where lake effect snows should bring 3 to 6 inches of snow over a
24 to 36 hour period.

The models are now in better agreement about a possible snowfall
Saturday night and Sunday as a surface low moves from southeast
Colorado towards the Great lakes. Looks like an advisory level
snowfall is possible with 3 to 5 inches or so. Then some colder
air will arrive for next week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1053 AM CST Tue Dec 6 2016

Continued IFR cigs and vsby are expected ahead of and along a cold
front pushing through the state this afternoon. The main bulk of
precip should be in central and northern Wisconsin through the
early afternoon before the line of precip starts to dry up as is
encounters the very dry air in eastern Wisconsin. A widely
scattered rain or even snow shower is possible in eastern TAF
sites this afternoon, however not enough confidence at this time
to include it in those TAFs.

Behind the front, Cigs and vsbys will improve. Fog is not expected
tonight. Cigs should increase to MVFR, with clouds possibly scattering
out with VFR conditions for a time overnight in eastern central
and southern Wisconsin. Further north and west, MVFR cigs should
prevail through the night, with the lowest cigs in northern
Wisconsin. Gusty west winds will also develop behind the front
tonight and continue on Wednesday.

Wednesday should be dry until late afternoon or evening when lake
effect snow develops and should sneak into the snowbelt region of
the Northwoods.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....Allen
LONG TERM......RDM
AVIATION.......Allen


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