Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 260810

Area Forecast Discussion
National Weather Service Green Bay WI
310 AM CDT FRI AUG 26 2016

Forecast discussion for routine morning forecast issuance

Issued at 307 AM CDT Fri Aug 26 2016

Turning more humid again with showers and a few thunderstorms
tonight into Saturday.

On the large scale, ridges are located over the eastern Pacific
and over the southeastern United States, with a trough extending
from Hudson Bay to the intermountain West. The trough will weaken
over the next several days as the bulk of the energy within it
shifts off to the northeast. That will leave a fairly zonal band
of westerlies across the northern CONUS and southern Canada by
late in the weekend. Then for next week, medium range models are
in pretty good agreement that a sharp/fairly deep trough will
develop just off the West Coast. Much more uncertainty exists on
the amplitude/position of the downstream ridging, and the eastern
NOAM upper trough likely to form downstream from that.

Temperatures will be a bit cooler today and held back again
tomorrow by rain before returning to modestly above normal for
Sunday and early next week. Uncertainty in the temperature
forecast increases greatly by the middle to end of next week as it
will depend on the position/amplitude of the eastern NOAM upper
trough. The precipitation event tonight and Saturday looks a
little less robust than it did yesterday. But the likelihood of
another opportunity for precipitation early next week has
increased. Though confidence in estimating total precipitation
remains low, the best estimate is for near normal amounts for the

.SHORT TERM...Today...Tonight...and Saturday
Issued at 307 AM CDT Fri Aug 26 2016

Fairly quiet today. Will maintain low PoPs across the far north
this morning as low-amplitude shortwave crosses the region.

The overall trend on the models since yesterday has been to slow
the arrival of the precipitation tonight, and to back down on
amounts for the event. In fact, a few of the models suggest there
could be less than complete areal coverage of the precipitation.
Adjusted forecast to slow the arrival of the rain, and kept the
highest PoPs confined to likely category due to uncertainty in
everyone getting rain. Even elevated instability is progged to be
very limited by the ECMWF, GFS, and NAM. So although some thunder
remains in the forecast, continued to downplay it and kept
dominant precipitation type as SHRA.

.LONG TERM...Saturday Night Through Thursday
Issued at 307 AM CDT Fri Aug 26 2016

Pattern shift expected to occur during the middle and end of next
week. Zonal flow at 500mb will shift to a west-northwest pattern.
This pattern shift will lead to a significant cool down, especially
for the eastern Great Lakes and New England region. The western
Great Lakes region will see a cool down as well, but not as sharp
as locations farther to the east. Some of the models have 850mb
down to 0C or slightly below across eastern Canada near Hudson Bay.

For Saturday night, lingered chances of showers and perhaps a
thunderstorms during the evening hours. Highest chances were
across northeast Wisconsin. A slight chance of showers will
continue across much of the region after midnight. Attention then
turns to precipitation chances Sunday through Wednesday. Latest
gfs/wrf were already bringing precipitation back into the region
Sunday or Sunday night. Since this was a significant change from
last night, trended heavily toward the ECMWF and to some extend
the Canadian model during this period. Above normal temperatures
will continue through the middle of next week, then return closer
to normal by the end of next week.

.AVIATION...for 12Z TAF Issuance
Issued at 307 AM CDT Fri Aug 26 2016

Expect more in the way of diurnal convective cloudiness today,
though bases should be primarily VFR. The exception may be across
the north this morning, and will make issuance time decision on
whether or not that warrants carrying tempo MVFR cigs in the RHI
TAF. Lower clouds will overspread the area as precipitation
advances north tonight, but given the slower arrival now
anticipated, VFR conditions are expected for at least the bulk of
the night.



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