Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 280333

Area Forecast Discussion
National Weather Service Green Bay WI
1033 PM CDT SAT AUG 27 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 322 PM CDT Sat Aug 27 2016

Water vapor imagery shows a vigorous mid level shortwave across
the upper Mississippi Valley coincident with an area of showers.
There will be a continued chance for showers, with a much lesser
thunderstorm threat, through the evening hours as this feature
passes through to the north. Despite the upstream thunderstorms,
the timing of this feature passing through the area, after peak
heating, is such that the thunderstorm risk should diminish by the
time it reaches the area.

Once the shortwave tracks east, weak high pressure will settle in
across the area later tonight. The light winds and abundant low
level moisture afforded by the recent rainfall will lead to an
increased threat for fog after midnight. Given the latest MOS
guidance categories, will raise patchy fog to areas of fog for the
area late tonight and into early Sunday morning. Despite the
threat for fog, dense fog advisories are not anticipated as dense
fog should be patchy and transient. If dense fog proves more
persistent and widespread this will be re-evaluated with
subsequent shifts.

A warm and somewhat humid day is expected on Sunday as the weak
high shifts slightly east. There is a chance for showers and
thunderstorms across north-central Wisconsin during the afternoon
hours as a mid level shortwave tracks through northwest Wisconsin.

.LONG TERM...Sunday Night Through Saturday
Issued at 322 PM CDT Sat Aug 27 2016

Weak zonal flow over northern conus early to quickly transition
toward more amplification by midweek. Devil in details as model
guidance offers varying solutions as to evolution of shortwave
impulses traversing the US/Canadian border downstream of
amplifying ridge over intermountain west. Forecast confidence low
thus preferred to make only minor adjustments to previous forecast
for early next week as frontal boundary over Dakotas moves east
toward Wisconsin by 00Z Tuesday. Maintained only low pops across
the north early Sunday evening as modest WAA kicks in across the
Northern Mississippi Valley. Appears best chance for shower and
thunderstorm activity will be with primary surface frontal boundary
forecast to enter forecast area Monday night into early Tuesday.
Much uncertainty remains as to where convection will focus along
the boundary. Best guess is bulk of activity will occur after 06Z
through about 18Z Tuesday with more widespread activity generally
southwest of the forecast area where deeper moisture and
instabilityto exist. Overall forcing and instability over
Wisconsin not impressive thus expect activity to remain scattered,
of modest intensity and to remain below severe limits. Leaned
toward somewhat more progressive ECMWF with any lingering
precipitation clearing the forecast area by early Tuesday evening.

High pressure to build into the area by Wednesday with a generally
dry and pleasant period for the remainder of the work week.

.AVIATION...for 06Z TAF Issuance
Issued at 1032 PM CDT Sat Aug 27 2016

Instrument flight rules conditions expected across the area
tonight. Ceilings may fall below minimums in some locations until
around 13z or 14z. Drier air will produce some clearing by midday
Sunday with VFR conditions expected in the afternoon.




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