Area Forecast Discussion
Issued by NWS Green Bay, WI

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548
FXUS63 KGRB 050547
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1147 PM CST Sun Dec 4 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Monday
Issued at 301 PM CST Sun Dec 4 2016

The latest rap analysis and satellite/radar imagery show a
relatively sharp shortwave trough moving into the northern
Mississippi Valley early this afternoon.  A swath of light to
moderate snow continues to move northeast across the region ahead of
this trough, but accumulations have struggled to occur on the
primary roadways based off of area webcams. Looking at road
temperature forecasts, potential remains for accumulations on
roadways to occur late this afternoon and this evening as pavement
temps cool. Wet pavements could also become icy.  The back edge of
the snow is currently pushing across Eau Claire and should start
moving into Wood and Marathon counties between 4 and 6pm. Forecast
concerns revolve around snow accumulation trends and amounts
tonight.

Tonight...Followed the HRRR for timing the back edge of the swath of
snow.  This back edge should proceed east across central and north-
central WI between 5 and 8 pm, and northeast WI between 8 and 11 pm
tonight.  As road temperatures cool with the sun going down,
anticipate travel conditions to become increasing treacherous late
this afternoon into this evening.  This will likely have bigger
impacts to eastern WI than farther west, since an additional inch or
two of accumulations will be possible during this time in this area.
In total, still think 2 to 4 inches looks about right for the
advisory area, perhaps lower right along the Lake Michigan
shoreline.  Once the snow departs, roughly around midnight, partial
clearing could arrive from southwest to northeast late.  Lows should
not fall much due to the clouds and a persistent southwest wind.
Mins in the middle to upper 20s look about right.

Monday...Weak ridging will move across the area during the morning,
which could result in a few hours of partial sunshine.  Then
southwest winds aloft will bring in mid and high clouds in a warm
advection regime late morning through the afternoon.  Moisture could
become deep enough for some flurries or light snow over far north-
central Wisconsin during the afternoon.  Highs in the mid to upper
30s.

.LONG TERM...Monday Night Through Sunday
Issued at 301 PM CST Sun Dec 4 2016

Upper troughs pass north and south of Wisconsin Monday night and
Tuesday. The one to the north looks strong enough to bring some
snow showers to the region, but no accumulations expected.
Blustery and colder weather arrives Tuesday night and Wednesday as
surface high pressure moves in.

AN upper trough moving slowly across the region Wednesday night
through Thursday night will produce some upper support and shift
low level winds to the northwest and make lake effect snow
possible for far north central Wisconsin. Several inches of snow
possible in Vilas county from early Thursday through Friday. The
remainder of the forecast area should be dry and cold.

There is a chance of a light snowfall Saturday as a trough
approaches from the west.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1136 PM CST Sun Dec 4 2016

Patchy light freezing drizzle will come to an end early in the TAF
period. Low clouds should gradually improve from IFR to MVFR
overnight. Although clearing skies are not a certainty, have
hedged bets that clearing will occur as a surface ridge axis
arrives late tonight into Monday morning. There is already a
pronounced clearing line in southeast MN and eastern IA, so there
is evidence that this may occur. MAV guidance also supports this
scenario. Most locations should have VFR conditions with mainly
mid and high level clouds from late morning through early evening.

LLWS is expect to develop in the late afternoon or early evening
as south winds increase to 35 to 45 kts just off the surface,
as low pressure approaches from the Northern Plains. Clouds will
thicken over north central and central WI in the late evening, and
ceilings may lower to MVFR toward the end of the TAF period.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch



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