Area Forecast Discussion
Issued by NWS Green Bay, WI

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342
FXUS63 KGRB 122357
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
657 PM CDT Sat Aug 12 2017

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 224 PM CDT Sat Aug 12 2017

The latest RAP analysis and satellite/radar imagery show high
pressure centered over the northern Mississippi Valley early this
afternoon.  Skies are mostly clear to partly cloudy across the
region, with only high based cu present.  Looking upstream,
shortwave troughing is slowly moving east over the northern Plains,
with scattered showers and storms over the Dakotas.  As this
shortwave moves east, clouds and temps are the main forecast
concerns.

Tonight and Sunday...Once the high based cu dissipates, high
pressure will provide mostly clear and quiet conditions for much of
the night.  Will start to see cirrus move into north-central WI late
tonight ahead of the shortwave.  But the cirrus should not hold up
temps much, so will continue to side with the colder guidance for
lows.  Min temps should range from the lower to mid 40s in the cold
spots to mid 50s near the Lake.

Mid and high clouds will continue to increase across the region
through the day as the shortwave energy arrives from the west.  It
will run into a much drier airmass below 600-700mb, as deeper
moisture will remain west of the region.  But combined with some
high based cu once again, should see skies turn partly sunny to
mostly cloudy after a relatively sunny start.  Temps will be near
todays readings, perhaps a degree warmer.

.LONG TERM...Sunday Night Through Saturday
Issued at 224 PM CDT Sat Aug 12 2017

Return flow behind departing surface high will bring increased low-
level moisture to area late Sunday and Monday. Weakening
shortwave trof will move across the state Monday with attendant
shower/storm chances.

Energetic jetstream over north Pacific undercuts block over
central Canada with another shortwave trof moving into Upper
Midwest late Tuesday-Wednesday. Models in general agreement on
this scenario, although GFS is a bit more aggressive with
convection. Yet another shortwave trof moves in later in the week
as Pacific energy continues to generate fast-moving systems. GFS
again a bit stronger with late-week system.

Temperatures should generally be near or above normal during the
upcoming work week.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 657 PM CDT Sat Aug 12 2017

Mostly clear skies expected tonight, with ground fog
possible for a few hours around sunrise. VFR conditions forecast
Sunday with some middle and high clouds arriving from the west.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......JKL
AVIATION.......RDM



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