Area Forecast Discussion
Issued by NWS Green Bay, WI

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119
FXUS63 KGRB 281925
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
225 PM CDT THU JUL 28 2016

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Friday
Issued at 225 PM CDT Thu Jul 28 2016

The latest RAP analysis and satellite/radar imagery show weak areas
of low pressure spinning over southwest Wisconsin and also over
central Illinois.  Convergence created by these surface lows along
with weak mid-level shortwaves is generating scattered showers over
central and northeast Wisconsin, and thunderstorms downstate.
Showers appear to be more aligned with mid-level convergence from
Wausau to Sturgeon Bay, but additional shower activity is developing
further south than this line.  As another wave arrives from
Minnesota later today, a moist airmass with pwats upwards of 1.7
inches will support showers continuing through the afternoon.  Precip
trends are the main forecast concern in the short-term.

Tonight...Weak shortwaves will continue to march east across the
region, while low pressure gradually slides to the south.  Short
range model guidance also drops the scattered shower activity
southward, but considerably slower than the previous model cycle.
Furthermore, most guidance now hangs shower activity through the
night over east-central WI as a comma head of one of the shortwaves
moves overhead.  As a result, kept a chance of showers in the
forecast for central WI through 06z, and northeast WI through 12z,
while also slowing down the clearing trend.  Farther north, should
see mostly clear skies and light winds, which could drop temps into
the 40s along the U.P. border. Lows in the mid 50s to low 60s over
central and east-central WI.

Friday...Skies will remain partly to mostly cloudy over central and
east-central WI for the morning.  A slight chance of a shower will
be possible with daytime heating from Wautoma to Oshkosh. Otherwise,
it appears drier air will make gradual progress into the region from
the north.  Should still have ample cu formation but that should not
stop highs from warming into the mid to upper 70s.

.LONG TERM...Friday Night Through Thursday
Issued at 225 PM CDT Thu Jul 28 2016

Canadian high pressure and associated drier air will be ridged
across the northern Great Lakes through the weekend. Although a
few models generate spotty and weak afternoon convection at times,
the general concensus is for a dry period from Friday night
through Monday, along with a gradual warming trend.

As the Canadian high shifts east Monday night into Wednesday,
southerly return flow will lift sfc/H8 warm fronts through the
forecast area, resulting in a chance of thunderstorms. The chance
of storms will continue Wednesday night into Thursday, as a cold
front moves through the western Great Lakes. Very warm and muggy
conditions appear poised to return during this period, along with
the potential for locally heavy rainfall, as precipitable water
values increase to 1.5 to 2 inches. Severe thunderstorm potential
may also increase, as moderate to strong instability develops
during the midweek period.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1214 PM CDT Thu Jul 28 2016

Weak upper level disturbances will move across the region for the
rest of today and through tonight.  Scattered showers will continue
because of these disturbances, mainly along and south of route 29
and south of Sturgeon Bay.  Fairly widespread Mvfr cigs are expected
to continue in this area, becoming locally ifr within any showers.
The clouds and showers are expected to gradually drop south tonight,
leading to improving ceilings over the central WI taf sites.
However, remained more pessimistic for the east-central WI taf sites
as guidance now suggests clearing may not occur until Friday.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......MPC



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