Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 240748
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
248 AM CDT Tue Oct 24 2017

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 247 AM CDT Tue Oct 24 2017

Active weather pattern this week with the development of a deep
low pressure system just northeast of the forecast area today for
starters. In addition to winds, colder air will provide the
chance for a rain/snow mix to North Central Wisconsin later
today.

Strong pressure gradient developing over Northeast Wisconsin will
produce near or wind advisory criteria for much of the area with
the peak of the wind gusts starting late morning or noon. In
addition to the stronger pressure gradient for Door County, winds
mixing down with wrap around showers also provide the potential
of near wind warning criteria. With the surface low progged to
stall and intensify over the eastern Upper Michigan and far
northern Lake Michigan with a 120 KT jet wrapping into the
system, will head to a high wind warning for Door County. Winds
may reduce to advisory criteria this evening and later shifts can
adjust as needed.

Colder air will pour into the region on very gusty northwest
winds. Temperatures across the north will turn cold enough for a
snow or snow mix before the system departs to the northeast later
today into early evening.

The upper trough will continue to deepen over the region late
tonight into Wednesday morning as a north to south 170 kt jet
drops over the western two thirds of the state including parts of
central and north central Wisconsin. The air mass will be cold
enough for snow or snow mix again, before warming to light rain
later Wednesday morning. Upper ridge begins to build into the area
later Wednesday with the upper trough shifting eastward. Quieter
weather with lighter winds and decreasing clouds will return
Wednesday afternoon.

.LONG TERM...Wednesday Night Through Monday
Issued at 247 AM CDT Tue Oct 24 2017

Focus of this forecast revolves around precip chances and precip
type during the Thursday night through Saturday period, when another
low pressure system slowly moves across the region.  The ecmwf and
gfs are in reasonably good agreement, so a blend of these models
should suffice.

Wednesday night through Thursday night...Some low clouds may linger
over east-central WI within a low level convergence zone behind a
fast moving clipper.  Though it appears these low clouds will depart
relatively early in the evening, they look to return to eastern WI
late Wednesday night into Thursday morning when low level flow
becomes southeasterly off the Lake.  Wouldnt be surprised to see
some drizzle or a few light showers develop on Thursday along the
lakeshore.  At the same time, a potent low pressure system will be
moving across the northern Mississippi Valley on Thursday and
Wisconsin on Thursday night.  Forcing will increase ahead of the low
on Thu afternoon into Thu night, with upper divergence and mid-level
fgen focusing the heaviest precip over northern WI.  Though temps
look too warm for any accumulations in the evening, the column may
cool enough for an inch of snow on grassy surfaces late Thu night
over n-c WI. No significant changes to temps.

Rest of the forecast...As the low lifts northeast over northeast WI
and the Upper Peninsula, colder air will be wrapping in behind the
low on Fri and Fri night.  The air looks to be cold enough for a
rain/snow mix over north-central WI on Fri, and possibly changing
back to all snow north and west of the Fox Valley on Fri night.
Perhaps a dusting to a half inch to an inch of accumulations will be
possible. Rain and snow showers look to continue for much of Sat
before ending on Sat night as the low finally moves away.  Quieter
weather then returns on Sunday.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1034 PM CDT Mon Oct 23 2017

Low pressure will intensify as it moves north across lower Michigan
to near Sault Sainte Marie. It will remain in that area for the
next day or so. It will produce strong northwest winds across
most of Wisconsin, especially the northeast quarter of the state.
The winds could produce crosswind restrictions at some airports.

Rain showers and MVFR conditions will accompany this storm system
tonight through Tuesday, with periods of IFR conditions with the
heavier rain showers.
&&

.MARINE...
Issued at 247 AM CDT Tue Oct 24 2017

A strong storm is forecast to deepen and remain nearly stationary
over eastern Upper Michigan and northern Lake Michigan Today
before shifting to the east tonight. Gale warnings are already in
effect for both the Bay of Green Bay and the nearshore waters of
Lake Michigan. Storm warnings have been posted for the open waters
of Lake Michigan.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 7 AM this morning to 7 PM CDT this evening
for WIZ005-010>013-018>021-030-031-035>040-045-048>050-073-074.

High Wind Warning from 6 AM this morning to midnight CDT tonight
for WIZ022.
&&

$$

SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......RDM
MARINE.........TDH


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