Area Forecast Discussion
Issued by NWS Green Bay, WI

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137
FXUS63 KGRB 132100
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
300 PM CST Fri Jan 13 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Saturday
Issued at 300 PM CST Fri Jan 13 2017

Weak lift on the backside of a surface high pressure ridge
drifting over the Great Lakes region through tonight generating
mid level clouds with scattered flurries over Minnesota this
afternoon. This region of lift is expected to weaken but still
slide over the forecast area tonight.  Will keep a flurry mention
going tonight as the arctic air departs the area.

Overnight low temperatures highly dependent on cloud trends
tonight. Latest sat imagery suggests far northeast Wisconsin may
have a bit more time under clears skies, resulting with evening
plummeting temps. Mid to high clouds over east central Wisconsin
also thinning a little this afternoon. If clouds depart quicker
toward early Saturday morning over central and north central
Wisconsin, potential of another quick fall in temps.

Quiet weather to continue into Saturday as the surface high
pressure area remains settle over the region. Continued weak warm
air advection will continue the moderating temperature trend for
the weekend.

.LONG TERM...Saturday Night Through Friday
Issued at 300 PM CST Fri Jan 13 2017

Focus remains on the next winter storm due to impact the region
early next week.  The medium range models have diverged a bit with
their latest runs, in regards to the track and timing of the low as
it moves across the western Great Lakes.  This divergence is most
likely related to how each model handles the interaction between
this system and a northern stream wave as it digs into the northern
Plains on Monday.  The 12z gfs looks way too strong with the
northern wave, and prefer a solution more towards the ecmwf and
canadian.

Saturday night through Sunday night...Mainly quiet during this
period thanks to arctic high pressure present across the region.
Temperatures will be moderating some during the daylight hours, with
highs returning into the middle 20s on Sunday.  Temperatures will
likely remain cold on Saturday night, due to clear skies and light
winds.  Will continue to side with the coldest guidance.  By late
Sunday night, clouds will be on the increase, with a small chance of
light snow pushing into central and east-central WI by daybreak.
Temperatures could fall well below forecast over north-central
Wisconsin before clouds arrive.  Will manually lower temps there.

Rest of the forecast...An active period of weather will return on
Monday thru Tuesday night.  Upper level low pressure will then track
northeast towards the western Great Lakes by late Monday night
before exiting the Great Lakes on Tuesday night.  The first push of
moisture/precip looks to arrive from south to north on Monday.
Precip type will be an issue right away as the precip arrives, with
warm layer temps near or above freezing, while surface temps will be
near or below freezing.  Even if surface temps do rise above
freezing in spots, colder ground temps could cause icy conditions to
occur.  So think that significant impacts from a wintry mix are
possible across much of north-central and northeast WI Monday into
Monday night, with some snow/sleet accums, and also some icing.
Surface temps are expected to rise above freezing late Monday night
over northeast WI, but it may take until Tuesday morning to see
improving conditions in this area.  While the threat for icing looks
reduced on Tuesday across the east, think concerns for icing will
remain for north-central WI where temps should remain near or below
freezing.  Precipitation will eventually diminish on Tuesday night,
and may transition back to snow for a brief time before ending.

Once the precip ends on Tuesday night, split flow will create a
couple days of quiet and mild weather, for Wednesday and Thursday.
Then another warm system could approach the region towards the end
of next week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1019 AM CST Fri Jan 13 2017

With high pressure drifting over the area today into
Saturday, VFR conditions to dominate. Mainly mid to high level
clouds passing over the region during the period.
&&

.HYDROLOGY...
Issued at 300 PM CST Fri Jan 13 2017

After a storm system with mixed precipitation departs next
Tuesday, a warming trend is expected for much of the remainder of
next week. Confidence is low that conditions will be in place for
a fast snowmelt causing flooding issues on area rivers and streams
late next week. After the tuesday storm system, rest of next week
overall dry and mild. However confidence is increasing that
forecast temperatures and melting of snow may produce enough
runoff to produce minor flooding on streets where storm drainage
systems are clogged.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......TDH
HYDROLOGY......TDH



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