Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 010349

Area Forecast Discussion
National Weather Service Green Bay WI
1049 PM CDT FRI SEP 30 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Saturday
Issued at 256 PM CDT Fri Sep 30 2016

Expect clouds and scattered showers across most of the area
tonight and Saturday, especially in eastern Wisconsin.

A closed upper level cyclone over the Ohio Valley today will
slowly move to the north through 00Z Sunday. Clouds wrapped around
the system are expected to spread across north central Wisconsin
by evening as it gets a little closer to the area. Have chances
for showers increasing from southeast to northwest tonight and
they decreasing from west to east on Saturday. It may stay dry
across much of north central Wisconsin before the clouds and
showers associated with the upper system drift eastward.

Highs on Saturday should be mainly in the lower to middle 60s,
with the warmer temperatures across the north where more sunshine
is expected.

.LONG TERM...Saturday Night Through Friday
Issued at 256 PM CDT Fri Sep 30 2016

Primary forecast challenges during this period centers on the
timing of the departure of the persistent upper low this weekend
and then the frontal system for the middle of the week next week.

Saturday night through Sunday night, the upper level low pressure
will be slowly drifting to the northeast over lower Michigan. In
addition to clouds wrapping around into the state, showers will
continue to spread into eastern Wisconsin. A ridge of high
pressure and drier air over central Wisconsin will tend to keep
showers to the east through Saturday night.

Clearing likely to work into the area late in the weekend as the
upper low departs. Light winds and clear skies may lead to
overnight fog formation.

Progs this morning have come in better agreement with respect to
the timing of an upper low with frontal boundary working across
the northern and central plains next week. Anticipate some timing
issues may linger in the coming days as the tropical storm or
hurricane track northward along the east coast next week. But
the latest timing suggests the frontal passage Wednesday into
Wednesday night followed with a dry slot toward Thursday, and
finally wrap around precipitation spilling into northern Wisconsin
on Friday.

Will keep a mention of thunder going next week, especially along
the front and ahead of the approaching dry slot. Total totals
climb to the upper 40s to near 50 with the front and lift from the
upper jet may play a role.

In the wake of system next week, medium range progs are
indicating a cooler air mass will pour into the area next Friday
or Saturday. Guidances suggests H850 temps as cold as -4 across
northern Wisconsin.

.AVIATION...for 06Z TAF Issuance
Issued at 1049 PM CDT Fri Sep 30 2016

An upper level low pressure system over the Ohio
Valley will continue to produce clouds across most of the area
tonight through Saturday night. SHowers are possible at times,
especially near Lake Michigan. VFR conditions should generally
prevail where it is not raining, with MVFR or IFR ceilings where
there are steady showers.Good flying weather is expected Sunday.



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