Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 211229

Area Forecast Discussion
National Weather Service Green Bay WI
629 AM CST Sun Jan 21 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 413 AM CST Sun Jan 21 2018

A storm track like this in mid winter is usually associated with
snow, but the lack of an arctic high to the north to deliver low
level cold air will result in more rain than snow across east
central Wisconsin, and a mix of snow, sleet and perhaps freezing
rain from Wisconsin Rapids to Shawano to Peshtigo. Significant
snow is still likely further to the north.

Today we will have middle and high clouds much like yesterday.
There may be areas of dense fog for a few hours this morning south
of highway 10. Temperatures well above normal and light winds should
make for a good day for winter sports.

Warm advection ahead of the winter storm will bring a mix of snow,
freezing rain and rain to all but the far north late tonight. Some
snow and ice accumulation is possible especially north and west of
the Fox Valley. Lows tonight will be in the 20s in the north and
in the low 30s in the south.

Significant snow is likely north of a Wausau to Crivitz line
Monday, mostly rain in the Fox Valley and lakeshore counties, and
a mixture of snow, sleet and rain in between. Northeast winds will
also become gusty across the east. Highs will be in the low to
mid 30s.

.LONG TERM...Monday Night Through Saturday
Issued at 413 AM CST Sun Jan 21 2018

Forecast concerns continue to revolve around the winter storm which
will exit the region during the Monday night into Tuesday morning
period.  Models are in much better agreement so a blend of the
ecmwf/nam/gfs should suffice.

Monday night through Tuesday night...Low pressure will continue to
move northeast from the IL/WI border at 00z Tue to Lake Huron by 12z
Tue.  The heaviest precip will reside in an arcing band within the
trowal airstream and mid-level deformation zone which will mainly
impact northern WI.  Central to northeast WI will see the mid-level
dry slot overhead for much of the night, with the loss of ice
crystals leading to periods of drizzle/freezing drizzle mixing in
with light snow at times.  There is a chance that deeper moisture
will return into east-central WI late Monday evening into Monday
overnight that could lead to an inch or two of snow, but many models
also push it further east and bypass the region.  So putting it
together, it appears that 2 to 4 inches of additional accumulations
are possible over northern WI on Monday night into Tuesday morning.
It also appears possible that a winter weather advisory will be
needed for central to northeast WI for freezing drizzle within the
dry slot once temps cool below freezing by mid-evening.  Precip
should end as light snow and flurries for most locations on Tuesday
morning, with gusty northwest winds and blustery conditions.  Clouds
look to depart on Tuesday afternoon as high pressure builds into the
region.  Some mid-clouds arrive for Tuesday night and could see a
few flurries, but likely of little consequence.

Rest of the forecast...Other than a weak clipper providing a chance
of flurries over northern WI on Wednesday into Wednesday night,
quiet weather will prevail through Friday.  After temps return to
normal on Tuesday and Wednesday, should see another warm up take
place on Thursday and Friday.  The next system remains on track to
move across the area on Friday night and Saturday.  Track of the low
is west of the region, so impacts should not be nearly as
significant as the upcoming system.

.AVIATION...for 12Z TAF Issuance
Issued at 629 AM CST Sun Jan 21 2018

Areas of low clouds and fog will produce a few hours
of IFR conditions south of a Wausau to Green Bay line this
morning. Mostly VFR conditions are expected this afternoon and
evening, then an approaching winter storms will bring snow, sleet
and rain to the region with IFR conditions late tonight through
Monday night.

Winter Storm Watch from Monday morning through Monday evening
for WIZ005-010>013-018-019-021-030-073.


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