Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 201237 AAA
AFDGRB

Area Forecast Discussion...UPDATED
National Weather Service Green Bay WI
637 AM CST Fri Jan 20 2017

New Information added to update section

.UPDATE...
Issued at 635 AM CST Fri Jan 20 2017

Will update to expand the freezing rain advisory northward a tier
as area surface temperatures remain below freezing and the band
of freezing rain and rain will reach the area the next few hours.
Also trending to canceling part of the dense fog advisory over
east central Wisconsin as visibilities have improved. There is the
potential that dense fog could redevelop over east central
Wisconsin as the rain diminishes later morning. But at this time
no sites reporting dense fog and web cams have showed plenty of
improvement.

&&

.SHORT TERM...Today...Tonight...and Saturday
Issued at 248 AM CST Fri Jan 20 2017

A messy period of weather through Saturday with mixed
precipitation along with fog. The fog will be dense at times.

A northwest to southeast band of mixed precipitation associated
with a mid level short wave trough will continue to lift north
today. Mixed precipitation consists of mainly rain or freezing
rain depending on surface temperatures. Plenty of lower 30
temperatures centered over central Wisconsin early this morning,
so running freezing rain advisory looks ok to continue. Within
this band of precipitation, subtle vorts will moving within this
band. A first piece was moving into west central Wisconsin early
this morning, with a second piece over lower Lake Michigan moving
toward east central Wisconsin this morning. For locations at or
just above freezing, will leave freezing rain advisory run its
course as cold surfaces likely enough to produce icy conditions.
Dense fog was located north of this band and along the lakeshore,
but diminished as the mixed precipitation moves in.

After a diminished period of precipitation late today into
tonight...another short wave slides north over the area in the
southwest flow aloft. Precipitation expected to be less than
todays event and forecast temperatures appear a few degrees
warmer. Will confine any freezing mention to the north late
tonight into Saturday morning with surface temperatures near
zero. Increasing surface dewpoints and above freezing
temperatures will likely keep the threat of fog, locally dense,
through Saturday.

Noticed Thursday afternoon temperatures varied from the mid 30s
in the cloud cover over most locations to the mid to upper 40s
across the north where clouds cleared. Expect clouds to be more
widespread with less of a chance of a wide range in max
temperatures this afternoon.

.LONG TERM...Saturday Night Through Thursday
Issued at 248 AM CST Fri Jan 20 2017

The medium range models are in better agreement through Monday
before diverging with the track/timing of a cyclone due to move
across the region during the middle of next week.  Forecast concerns
revolve around precip chances Saturday night into early next week.

Saturday night through Sunday night...An area of low pressure will
be lifting north across Minnesota on Saturday night and Sunday, and
will slowly push an occluded front northeast across the region.
Soundings continue to look relatively saturated at times on Saturday
night ahead of the front, particularly over central and north-
central WI, which should be good for periods of showers and drizzle.
Some breaks in the precip look possible over central and east-
central WI behind the front as the saturation depth lowers, but it
is going to be tough to clear out, given the light winds and mild
south flow above the inversion.  Better chances of light precip
should occur over far northern Wisconsin on Sunday and Sunday night.
The column will be cooling off some over the western half of the
state during this time, so could see snow mix in with rain/drizzle
at times when saturation depth increases.

Rest of the forecast...That front may linger across far northern WI
on Monday and possibly Monday night before departing, which will
prolong the cloudy and unsettled conditions.  Models are starting to
converge on the track of the cyclone progged to move across the
region mid-week.  But still sufficient differences to get a good
handle on the potential conditions.  Then turning colder with
periods of snow showers behind the system to end the work week.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 443 AM CST Fri Jan 20 2017

LIFR/IFR conditions will continue this morning.
Depending on surface temperatures, a band of light rain or
freezing rain will spread northward this morning. Ceilings and
visibilities will improve slightly this afternoon but may
deteriorate again tonight.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory until 10 AM CST this morning for
WIZ010>013-018>021-030-031-035>037-045-073-074.

Dense Fog Advisory until noon CST today for WIZ011>013-021-022-
073-074.
&&

$$

UPDATE.........TDH
SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......TDH


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