Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 291707
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1207 PM CDT FRI JUL 29 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 300 AM CDT Fri Jul 29 2016

Slow moving short wave trough continues to track over mainly the
south half of the state and producing scattered showers and
isolated storms over east central Wisconsin early this morning.
Pieces of energy in this trough were generating spotty convection
over the south half of the state. First piece will be departing
eastern wisconsin this morning while a second piece was over west
central Wisconsin. This second area is progged to pass over
southern wisconsin this afternoon. With pwats still near 1.50
inches and a very slow movement with the convection, isolated
heavy rainfall will continue with a few of the these showers and
storms early this morning.

Forecast challenge today continues with the convection trend today
starting this morning. Surface dewpoints were falling across
North Central Wisconsin early this morning as surface high
pressure builds into the area. But since surface dewpoints still
near 60 under the trough, will linger isolated shower and storm
mention today over east central this morning and then areas south
of highway 10 this afternoon and early evening. Anticipate a
little drier air to work south today but progs still indicating
upper 50 dewpoints for GRB though Saturday.

Models divert on additional isolated shower activity for Saturday
and the water vapor loop upstream showed weak waves upstream in
the noisy northwest flow. Upper heights do begin to increase later
Saturday so will continue with the dry forecast for now.

Clouds lingering this morning over much of central Wisconsin and
east central Wisconsin may hold back temps again today. But the
potential of breaks in the clouds occurring later morning between
the subtle pieces of energy in the trough prevent lowering max
temps at this time.

.LONG TERM...Saturday Night Through Thursday
Issued at 300 AM CDT Fri Jul 29 2016

Fairly zonal flow at 500mb will dominate the weather pattern
through the period. At the surface, high pressure will bring
dry conditions Saturday night through Monday. Models diverge on
the evolution of convection across the Upper Midwest and Great
Lakes region Monday night into Tuesday. Since the 00z ECMWF model
has been more consistent than any other model for this period,
will trend toward the ECMWF with a round of storms moving across
the area later Monday night into Tuesday morning.

Beyond Tuesday, confidence is low on timing of convection Tuesday
night through Wednesday night. Based on the 00Z ECMWF, there is
a better chance of thunderstorms Thursday afternoon and Thursday
night. High temperatures should be above normal through much of
the period.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1207 PM CDT Fri Jul 29 2016

A weak upper level trough will slowly drift over the state today
into this evening. Ceilings will likely remain mvfr over central and
east-central WI until late this afternoon or mid-evening, with
isolated showers possible generally south of a Wausau to Manitowoc
line.  Coverage is too limited to include in the tafs, though higher
probability of a shower exists at Oshkosh and Manitowoc. Model
guidance indicates that ceilings will improve this evening as drier
air finally moves in from the northeast.  Flying weather looks good
for Saturday.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......Eckberg
AVIATION.......MPC



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