Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 161034

Area Forecast Discussion
National Weather Service Green Bay WI
534 AM CDT Wed Aug 16 2017

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 325 AM CDT Wed Aug 16 2017

Primary issue during this period is the slow passage of a deep
upper trough and frontal system. This system early this morning
was producing widespread heavy rainfall over nebraska with
isolated severe weather.

Area radars show a band of warm air advection showers and isolated
storms on the leading edge of the 850 moisture convergence drifting
north or northeast over southeast minnesota and far western
wisconsin. Its possible a few of these showers may brush over
parts of central Wisconsin this morning, west of Wisconsin Rapids
and Wausau during the morning hours, while the rest of the area
is protected by the high pressure area.

Otherwise the system is progged to work into the state during the
evening hours and produce a widespread rain to the area. Pwats
climb into the 1.50 to 2.00 inch range tonight with the higher
values progged to be over the south half of the state.
Instability appears minimal with this system, but a weak upper
jetlet passing near the Wisconsin/Illinois border may provide some
weak shear to the southeast half of the state to produce a few
stronger storms. Likely area of heavier rainfall amounts will be with
the deformation area over northwest Wisconsin and northwest of
the surface low track, and convergence along and north of the 850
mb front lifting into the state later this evening and overnight
and likely continuing into Thursday morning across the north.
Latest timing of the surface cold front passage appears to be
from southwest Wisconsin Thursday morning, before departing
eastern Wisconsin Thursday mid afternoon. Some potential of
stronger storms along and ahead of this cold front over the south
half of the state. Instability again limited over much of northern,
but some instability may be available Thursday over southern
Wisconsin which may briefly work into parts of central and east
central Wisconsin ahead of the cold front. Depending on overnight
convection, the surface warm front may work into central and east
central Wisconsin Thursday morning before the cold front passage.

.LONG TERM...Thursday Night Through Tuesday
Issued at 325 AM CDT Wed Aug 16 2017

Conditions begin to quiet down in the extended period through the
weekend. Precipitation is likely to continue overnight Thursday
into Friday morning, but thunderstorm activity will die off
quickly as the upper level trough exits the region. Weak high
pressure will then move in Friday afternoon and last into the
early overnight hours.

Another brief upper level disturbance will then pass through the
area early on Saturday, creating another chance at some showers
and possibly isolated thunder, but support and instability for
any widespread thunderstorm activity will be lacking, given the
morning arrival. Dry conditions return to end Saturday and will
then last through most of Sunday as warm air once again presses
into the region. Active weather is then likely to return late
Sunday into Monday morning, with any chances of severe weather and
stronger thunderstorms holding off until Monday night into

Temperatures through the period will be close to normal heading
into the weekend, before rising to several degrees above normal by
Sunday and the start of next week.

.AVIATION...for 12Z TAF Issuance
Issued at 534 AM CDT Wed Aug 16 2017

IFR/MVFR ceilings will linger over north central and
parts of central and northeast Wisconsin this morning before
dissipating and improving to VFR conditions. Patchy MVFR/IFR vsbys
due to fog will also diminish shortly after daybreak. VFR
conditions then to prevail today into early evening. Conditions
expected to deteriorate later evening, overnight and into Thursday
morning as a frontal system spreads IFR clouds, rain and isolated
storms across the area.



LONG TERM......Uhlmann
AVIATION.......TDH is the U.S. government's official web portal to all federal, state and local government web resources and services.