Area Forecast Discussion
Issued by NWS Green Bay, WI

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219
FXUS63 KGRB 230343
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1043 PM CDT FRI JUL 22 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Saturday
Issued at 226 PM CDT Fri Jul 22 2016

Sunny skies and less humid weather prevailed across the cwa this
afternoon. This quiet weather is expected to persist into the
overnight hours with a high pressure in control of the western
Great Lakes. However light winds, clear skies, and remaining low
level moisture could once again lead to some patchy fog formation.
Lows tonight are forecast to settle into the 60s.

The main forecast concern on Saturday will be the possibility for
afternoon convection ahead of an approaching cold front. The
models offer many different solutions Saturday, with some models
developing an MCS that tracks into central Wisconsin by Saturday
afternoon, with other models dry for much of the afternoon. Given
the models performance as of late has been less than stellar and
the best instability remains to our southwest on Saturday prefer
the slower solution with this forecast. Therefore will maintain
chancy pops across the western cwa in case this system pushes in a
bit faster, but shy away from likely pops as this solution is not
the expected outcome. Highs Saturday should be a degree or two
below today given debris clouds from upstream convection is
expected to track over the area, even if the system itself holds
off a bit. Heat indices are expected to rise into the upper 80s to
lower 90s, with a few readings in the middle 90s given the dew
points generally remain in the 60s. Therefore no heat headlines
are anticipated at this time.

.LONG TERM...Saturday Night Through Friday
Issued at 226 PM CDT Fri Jul 22 2016

Little change from previous forecast as low amplitude upper level
flow is expected over the region during most of this forecast
period.

Thunderstorms for Saturday night and Sunday are the primary
concern as cold front moves across Wisconsin and a mid level
short wave trough moves across the region. Still some question as
to exact location, but it appears an MCS of some sort will form to
the west and move east or southeast and weaken as it traverses the
forecast area. While instability and PWATs indicate likely POPs,
the eastward extent of the severe threat is still uncertain. SPC
Day 2 looks reasonable.

There will be a narrow window on Sunday for isolated convection
until the front passes through mid-day, but debris clouds and a
freshly overturned atmosphere make adding details to Day 3
convective chances difficult.

The next chance for precip will be later Tuesday/Wednesday as yet
another shortwave trof or two moves through.

Temps AOA normal through mid-week.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CDT Fri Jul 22 2016

Main concern for tonight will be some patchy fog, then
thunderstorm chances later Saturday afternoon and Saturday
night. With a moist air mass in place, expect some patchy fog
tonight with MVFR conditions expected at most places. Could not
rule out some IFR ceilings/visibilities in the typical spots
across the north. Winds will turn to the east/southeast Saturday
morning as next system approaches from the west. Thunderstorms
will be on the increase late Saturday afternoon, with a large
thunderstorm complex expected to move across the region Saturday
night. Some of the stronger storms could produce hail, strong
winds and torrential rainfall.

&&

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

$$

SHORT TERM.....Kurimski
LONG TERM......JKL
AVIATION.......Eckberg



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