Area Forecast Discussion
Issued by NWS Green Bay, WI

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298
FXUS63 KGRB 290850
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
350 AM CDT MON AUG 29 2016

Forecast discussion for routine morning forecast issuance

.SYNOPSIS...
Issued at 346 AM CDT Mon Aug 29 2016

Seasonably warm and rather humid today into Tuesday, then turning
cooler and less humid for the rest of the work week.

A gradual reamplification of the large scale pattern is expected
the next several days, with amplitude peaking late in the week.
The change will be driven by a strong upper trough that is
expected to deepen off the West Coast. That will lead to
downstream ridging initially forming over the Rockies and western
Plains, and another trough over eastern NOAM. The changes will
result in a turn to northwesterly upper flow across the forecast
area for the middle to latter part of the work week. Some eastward
progression of the large scale features will bring the upper
ridge into the Great Lakes region next weekend.

The warm and rather humid air mass currently across the area will
result in a couple more days with above normal temperatures, then
a few days of cooler and much drier weather with AOB normal
temperatures are expected for the rest of the work week. Readings
will begin to rebound next weekend as the upper ridge shifts into
the area. Precipitation opportunities will primarily occur early
in the period and be tied to low-predictability convective
systems, with very limited opportunities for precipitation during
the middle to latter part of the period.
&&

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 346 AM CDT Mon Aug 29 2016

What started as a small patch of Sc has rapidly expanded in the
past couple hours and now covers much of the forecast area. That
was keeping fog in check. Meanwhile, MCS continues to evolve over
northern Minnesota. Corfidi vectors for backward propagation were
veering to the south and southwest, and the strongest development
has shifted to the southwest side of the MCS. So there is
considerable uncertainty in how far east the storms are going to
get. May wind up with debris shifting into the northwest part of
the forecast area at some point this morning. Adjusted PoPs
accordingly.

The convective potential through the rest of the short-term is
somewhat muddled, so settled for a slow southeast advance of PoPs
through tomorrow. The severe potential will probably depend
primarily on how much destabilization can occur. Shear will be
relatively weak, and the flow above the surface is likely to turn
westerly or west northwesterly late tonight and Tuesday, even
ahead of the advancing cold front, so low-level convergence will
be limited as well. That usually results in limited thunderstorm
coverage. Given the moist air mass however, wet microbursts will
be possible, especially in situations where cell mergers occur.

.LONG TERM...Tuesday Night Through Sunday
Issued at 346 AM CDT Mon Aug 29 2016

As advertised the last several days, ridge will build across the
central United States with east coast trough across the eastern
portion of the country. This setup will bring the first real
taste of fall by the middle of the week. Temperatures by Friday
morning could dip into the upper 30s across the far north.

Except for a lingering shower or storm Tuesday evening, dry
conditions will prevail late Tuesday night through Saturday as
Canadian high pressure brings mild days and cool nights. Still
need to watch Thursday along the Lake Michigan shoreline.
Northeast winds off the relatively warmer waters of Lake Michigan
and cool air aloft could bring more cloudiness than currently
forecast. There is still the possible of lake effect rain showers
that could possible move onshore Kewaunee and Manitowoc counties.
Per coordination with surrounding offices, will hold of on adding
rain but did increase clouds in this portion of the forecast area.

Showers and thunderstorms could arrive later Saturday night or
Sunday, and continue at times into next Monday as well. It is too
early to determine severe potential. Did make some minor
adjustments to temperatures Wednesday through Friday to reflect
our typical warm spots during the day and the typical cold spots
at night.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 346 AM CDT Mon Aug 29 2016

Visibilities were fluctuating rapidly at some sites earlier in the
night, but have settled down some now that the Sc deck has
developed and Ci was overspreading the north. Could see some MVFR
ceilings with the Sc, otherwise expect mainly VFR conditions
outside of any thunderstorms than affect the area.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Eckberg
AVIATION.......Skowronski



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