Area Forecast Discussion
Issued by NWS Green Bay, WI

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716
FXUS63 KGRB 251959
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
259 PM CDT SUN SEP 25 2016

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Monday
Issued at 258 PM CDT Sun Sep 25 2016

Precipitation trends remain the main forecast focus over the next
24 hours, although increasing winds will create issues over the
bay and Lake MI on Monday.

The 19z MSAS surface analysis showed a cold front stretched from
northeast MN south-southeast into western WI, then south into
western IL. Some breaks in the clouds over eastern WI had allowed
temperatures to warm near 80 degrees and with dew points in the
upper 60s, thunderstorms had started to blossom over southern WI
which are headed northeast in our direction.

Showers/scattered thunderstorms will continue to track across the
rest of eastern WI this evening as the cold front sweeps eastward
through the region. Some semblance of a dry slot should bring a
brief respite to the precipitation for a time over central and
east-central WI overnight, however as a strong shortwave trough
pushes into the Western Great Lakes after midnight, increasing
cyclonic flow, mid-level shortwave energy and CAA will allow for
at least a chance of light rain showers across northern WI. A
tightening pressure gradient, steepening lapse rates and strong
subsidence behind the cold front will bring gusty west winds to
the area later tonight which will carry over into Monday. Min
temperatures will be in the mid to upper 40s north-central, upper
40s to lower 50s elsewhere except lower to middle 50s along Lake
MI.

The shortwave trough is progged to become a closed upper low over
southwest Ontario/Western Lake Superior on Monday. Cyclonic flow
to remain in place with individual shortwave energy rotating
through this mid-level trough. CAA, in concert with the cyclonic
flow and daytime heating, will bring an unsettled weather day
across the forecast area, especially the farther north you go.
Breezy conditions will also continue through the day with
sustained west winds of 15 to 25 mph and gusts that could approach
35 mph. It will also feel like autumn on Monday as max
temperatures are only expected to reach the lower to middle 50s
north, around 60 degrees elsewhere.

.LONG TERM...Monday Night Through Sunday
Issued at 258 PM CDT Sun Sep 25 2016

The upper low will move slowly south from Lake
Superior to the Ohio Valley by the middle part of the week. The
cyclonic flow and cold temperatures aloft will result in cloudy
skies and scattered showers, especially in the afternoon and in
the north. Temperatures are cold enough aloft for lake enhancement
to the showers in far northern Wisconsin and near Lake Michigan if
winds become northeast Tuesday or Wednesday.

The upper system moves far enough away for dry weather to follow
for the rest of the week if the GFS is correct. The ECMWF brings
the weakening upper system back towards the western Great Lakes by
the end of the week, which might bring showers to our area if
correct. Will leave it dry for now.

Cooler than normal temperatures are expected Monday and Tuesday
afternoons, but otherwise seasonable temperatures are expected.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1245 PM CDT Sun Sep 25 2016

Scattered showers/isolated thunderstorms will continue to affect
northeast WI this afternoon ahead of an eastward moving cold
front. Brief clearing to VFR conditions in the east will give way
to IFR/MVFR conditions as the front approaches. Precipitation
chances are expected to diminish behind the cold front with again
a brief rise in the cigs to VFR this evening. However, a strong
mid-level trough is forecast to move into the region later tonight
and send cigs down into the IFR/MVFR range late tonight. A
cyclonic flow around this trough is expected to keep plenty of
clouds around (mainly MVFR-based) on Monday along with a chance of
additional showers. In addition to the clouds and rain, west winds
could gust to 30 knots at times.
&&

.MARINE...
Issued at 258 PM CDT Sun Sep 25 2016

Behind the cold front, gusty west winds are expected Monday into
Tuesday. Gale force gusts are possible at times Monday afternoon
into Tuesday afternoon across the coastal waters of northern Door
County. Winds should begin to decrease later Tuesday afternoon and
Tuesday night.
&&

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

$$

SHORT TERM.....Kallas
LONG TERM......RDM
AVIATION.......Kallas
MARINE.........Kallas



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