Forecast Discussion for GRB NWS Office
FXUS63 KGRB 152011

Area Forecast Discussion
National Weather Service Green Bay WI
211 PM CST Sat Dec 15 2018

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Sunday
Issued at 210 PM CST Sat Dec 15 2018

The latest RAP analysis and satellite/radar imagery show high
pressure stretching from Texas to the Great Lakes early this
afternoon. Outside of some thin wispy cirrus dropping in from the
north, skies are mostly clear across the region thanks to ample
dry air at the surface and aloft. Looking to the west, a moisture
starved cold front is moving east across the northwest Plains.
With only mid and high clouds along the front, forecast concerns
mainly revolve around temps and fog potential.

Tonight...High pressure will continue to hang across the area
during the evening before shifting to the east overnight. A narrow
band of mid and high clouds will move from west to east overnight
along the front, but progged soundings indicate a dry atmosphere
below 15 kft. However, the pressure gradient will tighten along
the front, which should prevent temps from tanking and fog from
forming over central and north-central WI. Winds will be lighter
over eastern WI so could see some patchy fog develop there. No
significant changes to temps.

Sunday...The weak cold front will exit eastern WI by midday taking
most of the cloud cover with it. Some cirrus will likely still be
present overhead though should not impact temps much. Temps will
not be much colder behind the front, but should see highs fall
back a few degrees. Highs should range from the mid 30s to near

.LONG TERM...Sunday Night Through Saturday
Issued at 210 PM CST Sat Dec 15 2018

The Canadian low pressure trough to the north of Wisconsin will
sweep east of the Great Lakes region on Monday and make way for a
high pressure ridge. The upper air pattern is shaping up to be
rather amplified and progressive during the first half of the week
though, and a low pressure trough will rapidly sharpen over the
Plains States by Thursday, prompting the development of a surface-
based low pressure system over the Lower Mississippi Valley. This
low will draw Gulf of Mexico moisture north and produce a decent
chance for mixed precipitation in Northeast Wisconsin late
Wednesday through late Thursday.


.AVIATION...for 18Z TAF Issuance
Issued at 1028 AM CST Sat Dec 15 2018

Relatively quiet weather through the taf period. A dry cold front
will move across the area tonight. Increasing south winds aloft
will lead to llws developing from late evening through overnight,
mainly over north-central WI. The strengthening pressure gradient
should prevent fog from becoming an issue, but continued mvfr
vsbys over the eastern WI taf sites where winds will be lighter.




NWS GRB Office Area Forecast Discussion