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000
FXUS63 KGRB 200904
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
404 AM CDT Wed Jun 20 2018

Forecast discussion for routine morning forecast issuance

.SYNOPSIS...
Issued at 401 AM CDT Wed Jun 20 2018

A few sprinkles and showers across mainly the south this morning,
otherwise dry with seasonable temperatures for the rest of the
work week. Although rain chances will return this weekend, most of
the weekend will be dry with seasonable temperatures continuing.

The upper flow across North America will remain split with a
stronger branch of the flow across Canada and a weaker branch
across mainly the northern CONUS. A well defined frontal system
will remain stretched out along the southern band of the
westerlies, with very moist air in place along the front. Energy
progressing east across the CONUS will be suppressed south of the
area as the northern stream trough over eastern Canada amplifies a
little the next couple days. Then the forecast area will remain
primarily between the main branches of the flow until some
consolidation begins late in the weekend or early next week.

The main reservoir of very moist unstable air will remain far
enough south of the area throughout the period to allow for just
scattered light precipitation events and below normal totals for
the period. That will allow for an opportunity to dry out after
last weekend`s heavy rains. Temperatures should remain fairly
close to seasonal normals throughout the period.
&&

.SHORT TERM...Today...Tonight...and Thursday
Issued at 401 AM CDT Wed Jun 20 2018

Still having trouble getting the precipitation shifted completely
out of the area. Despite the surface front being well south of the
area, the forecast area remains within the frontal zone aloft.
Given plentiful moisture and a little elevated instability,
weakly frontogenetic flow was sufficient to generate isolated-
scattered sprinkles and showers again this morning. Those will be
most plentiful south and west of the area, but needed to carry a
mention of them through the morning for about the southern 1/3 of
the forecast area. Widespread clouds were preventing fog
formation, so removed that from the forecast for early today.

Drier air will edge southwest today, but guidance indicated mid-
level clouds will persist across the southwest portion of the
area all day. Started with a broad-based blend of guidance
products for max temps, then edged the southwest down a bit due to
the clouds.

Quite a bit of cloudiness along with scattered showers and some
thunderstorms were accompanying a frontal system dropping south
across Ontario early this morning. Low-level convergence along
the boundary will decrease substantially as the front begins to
shift south into the area late today, where the gradient will
already support northeast low-level flow. Bumped cloudiness up a
little over the north/northeast late today into this evening, but
kept forecast dry.

The front should wash out on Thursday, as the slightly cooler and
drier Canadian air behind the front pushes across the area on
northeast winds. Raised winds some near the lake and bay, and
edged temps back a little in those areas as well.

.LONG TERM...Thursday Night Through Tuesday
Issued at 401 AM CDT Wed Jun 20 2018

The ecmwf and gfs remain in relatively good agreement through this
part of the forecast and will continue to use a blend of their
solutions.  Forecast concerns mainly revolve around precip chances
this weekend.

Thursday night through Friday night...Low pressure will be slowly
moving east across the central Mississippi Valley on Thursday night.
The track appears to have shifted slightly further north compared to
solutions 24 hours ago, but the northern extent of the cirrus is
projected to barely reach into central WI, so will keep a dry
forecast intact.  Models then start to disagree slightly when to
start lifting the low to the northeast.  The latest solutions track
the low across central IL on Friday before turning the system to the
northeast on Friday night.  With the system pretty far south and
ample dry air present through the column, Friday looks to remain
dry.  Precip chances have diminished some for Friday night as a
further east track keeps most of the precip for the central and
eastern Great Lakes.  However, will keep a small chance mention for
northeast WI where will be on the western fringe of the system.
Little changes to temps over the period.

Rest of the forecast...As the system moves away from the region,
weak upper troughing will be moving across the region on Saturday
and Sunday.  Should see partly to mostly cloudy conditions at times,
through precip chances look too ill-defined for much of a precip
threat.  Finally, passage of a cold front will bring clearing skies
for the latter half of Sunday into Monday.  The next chance of
widespread precip does not look to arrive until next Tue.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 401 AM CDT Wed Jun 20 2018

Other than some patchy MVFR ceilings with scattered showers across
the south early today, generally good flying weather is expected.
Winds are expected to stay up enough tonight to prevent fog
formation.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......MPC
AVIATION.......Skowronski