Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 151145
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
645 AM CDT Tue Aug 15 2017

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 403 AM CDT Tue Aug 15 2017

A short wave trough with convection has departed east of the
state early this morning. Light winds and low level moisture has
produce fog across north central Wisconsin overnight. Forecast
soundings also show a morning inversion or saturated layer
gradually lifting today to indicate clouds may be persistent this
morning over part of the area.

Otherwise Canadian high pressure building into the area from the
north and an upper ridge sliding over the area will bring a
period of quiet weather to the area today into tonight.

Clouds will be on the increase Wednesday as a deeper upper trough
approaches form the Plains. Return flow precipitation will work
back into the state from west to east. Forecast soundings suggest
limited drying with the high pressure system today into tonight
with the light variable or northeast flow so convection may work
over the area a bit faster. Progs indicate minimal instability
Wednesday afternoon so thunder may be more confined to the upper
trough passage which would be in later periods.

.LONG TERM...Wednesday Night Through Monday
Issued at 403 AM CDT Tue Aug 15 2017

Active weather will stay in the area Wednesday night into
Thursday. Models continue to trend in favor of a rain event over
a severe one, with strong thunderstorm development remaining to
the south. Some embedded convection will likely still reach into
central Wisconsin if the warm front manages to push a little
further north, but instability is expected to become limited
quickly. Shear and CAPE values drop off rapidly overnight,
especially over northern Wisconsin. That said, precipitable water
values will increase to 1.5 to 2.0 inches during this time,
allowing for widespread heavy rainfall across the region.

Cold air advection will follow behind this system as it exits
Thursday morning to afternoon; which combined with a shortwave
and the influence of the lake, could bring in enough dynamics to
allow for a few more showers and isolated thunderstorms. High
pressure will then push into the region for Friday with primarily
dry conditions persisting across the region before the next round
of showers and thunderstorms could come across the region in the
weekend, along a frontal boundary.

Temperatures through the period will be within a few degrees of
normal through the weekend before rising to above normal by the
start of next week.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 645 AM CDT Tue Aug 15 2017

At 12z, conditions ranged from areas of IFR/LIFR
vsbys due to fog across north central Wisconsin, mainly IFR
ceilings across central Wisconsin, to mainly MVFR cigs over
northeast Wisconsin. Patchy IFR cigs were working into parts of
northeast Wisconsin early this morning. Anticipate the IFR/LIFR
conditions will persist this morning due to light flow under an
inversion. Conditions expected to improve to VFR later morning and
especially in the afternoon and then continuing into tonight.
Patchy IFR vsbys possible late tonight due to fog.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......Uhlmann
AVIATION.......TDH


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