Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
FXUS63 KGRB 150842

Area Forecast Discussion
National Weather Service Green Bay WI
342 AM CDT Tue May 15 2018

Forecast discussion for routine morning forecast issuance

Issued at 339 AM CDT Tue May 15 2018

Rather quiet spring weather. The next substantial chance for rain
won`t arrive until the weekend.

The upper flow across North America remains split along the West
Coast. The much stronger, dominant northern stream is across
Canada and the far northern U.S., while a weaker southern stream
is located across the central and southern CONUS. Only subtle
changes to the pattern are anticipated during the forecast
period, the most significant of which will be a modest
strengthening of the southern stream as an embedded upper trough
slowly migrates across the western states.

Some day-to-day temperature variations are expected as the
forecast area will be close enough to the northern stream to be
affected by cool fronts pushing south from Canada. But cool air
arriving in the area should moderate quickly, so temperatures will
vary between near and above normal. Precipitation chances with
the fronts will be modest at best, with the primary opportunity
for precipitation coming during the upcoming weekend as energy
ejects out of the southern stream trough. Amounts will depend
almost entirely on the specifics of that event and thus are tough
to gauge. The best estimate right now is for AOB normal amounts
simply because of limited opportunities for rain.

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 339 AM CDT Tue May 15 2018

Lingering showers in east-central Wisconsin will end early this
morning. Some fog may form in central Wisconsin as the mid-clouds
depart the area, but the early sunrise at this time of year will
work against widespread dense fog, which may develop to the
west/southwest of the area where clearing will occur while there
is still a few hours of darkness.

A strong northern stream shortwave will swing through eastern
Ontario this morning, then pull away to the east. The upper flow
tilting northwest behind that feature will help drive a cold front
south from the Lake Superior region. Winds turning northeast and
then east will bring cooling to eastern Wisconsin, with daytime
highs probably 8-15F degrees cooler than yesterday. The cooling
will be more modest out to the west.

Light winds and clear skies tonight should allow temps to drop
into the 40s in most areas, with some 30s possible in the far
north. Southwest winds ahead of another Canadian cold front will
result in warmer temperatures again Wednesday. Most areas away
from the lake and bay should reach the lower 80s.

.LONG TERM...Wednesday Night Through Monday
Issued at 339 AM CDT Tue May 15 2018

A zonal flow pattern at 500mb will continue into early next
weekend before a more substantial trough moves across the
western Great Lakes Saturday night into Sunday morning,
bringing a chance of showers and thunderstorms to the region.

For Wednesday night, a weak cold front will move into northern
Wisconsin Wednesday evening. This feature is expected to kick
off isolated shower activity across the north during the early
evening hours before much of the activity is expected to dissipate
by midnight. The weak boundary is then expected to drop southward,
thus there may be a sudden shift in the wind to the north or
northeast and a period of gusty winds across the Fox Valley and
lakeshore region. The northeast/east flow pattern will lead to
much cooler temperatures on Thursday from Green Bay and Appleton
east to the lake. Water temperatures across the northern Bay of
Green Bay and Lake Michigan were in the 40s. The southern Bay of
Green Bay has warmed into the lower to middle 50s. On the back
side of the high pressure system, there is a chance of showers
with the return flow Thursday afternoon across north-central
Wisconsin. Warmer temperatures return on Friday with highs in
the middle 70s to lower 80s away from the bay and lake.

The chances of showers and thunderstorms return Friday night, but
it appears the best chance of showers and storms will be Saturday
into Saturday night. It is too early to determine if any of the
thunderstorms would become severe at this time. Cooler weather
returns on Sunday behind the cold front. Seasonable temperatures
are expected on Monday under mostly sunny skies.

.AVIATION...for 12Z TAF Issuance
Issued at 339 AM CDT Tue May 15 2018

After some patchy MVFR/IFR conditions due to fog early today, good
flying weather is anticipated for the remainder of the TAF period
as a weak surface ridge crosses the area.



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.