Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 240334

Area Forecast Discussion
National Weather Service Green Bay WI
1034 PM CDT TUE AUG 23 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Wednesday
Issued at 241 PM CDT Tue Aug 23 2016

The latest RAP analysis and satellite/radar imagery show a shortwave
trough gradually lifting northeast over southeast South Dakota and
northeast Nebraska.  A relatively small cluster of showers and
storms is accompanying the shortwave, along with low clouds and
light showers spreading north over southern Iowa and northern
Missouri.  Starting to see high clouds ahead of the shortwave move
into central WI. Farther west, a cold front is moving east over the
central Dakotas, but is mostly inactive.  As the shortwave lifts
into the region late tonight, precip trends are the main forecast

Tonight...The shortwave trough over eastern South Dakota/Nebraska
will slowly lift northeast into Wisconsin late tonight.  Should only
see mid and high clouds arrive ahead of the system during the
evening, which should remain mild and breezy.  Then models point
towards low stratus developing ahead of the shortwave overnight when
increasing low level moisture arrives.  Additionally, models also
support showers and storms spreading from southwest to northeast
across the area late tonight.  Refined timing of precip chances a
little, but did not make many changes in regards to probabilities,
since concerns about coverage remain, given the low instability
progged for tonight. Models do show increasing shower/storm coverage
this evening over the northern Mississippi Valley, so this concern
may be unwarranted. With increasing clouds and higher dewpoints
expected, low temps will be warmer into the middle 60s.

Wednesday...The shortwave will continue to move across the region
during the morning, which will continue the chance of showers and
storms.  Concerns about coverage will carry over through the
morning, so capped precip chances in the likely range.  Between the
showers, could also see some drizzle or mist.  Drying will occur in
the mid-levels behind the shortwave as it exits during the
afternoon.  However, a cold front will be arriving during the the
afternoon, so will not be able to rule out additional showers
entirely, but only thinking isolated shower activity at best.  Low
clouds will be stubborn to improve ahead of the front.  With the
rain and clouds, muggy highs in the mid to upper 70s.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 241 PM CDT Tue Aug 23 2016

Model solutions are a little better now in pushing
the showers and thunderstorms out of our area by Wednesday late
evening. The upper flow remains cyclonic Thursday even though a
surface high is starting to move in from the west. A scattered
shower is not out of the question but will keep the forecast dry.

Dry and seasonable weather expected for Thursday night through at
least part of Saturday. Medium range models keep rain west of the
forecast area through midday, with showers and thunderstorms
Saturday afternoon or evening ahead of a weak cold front. Should
be dry Sunday afternoon and Monday before another system arrives
in the fast zonal flow along the U.S. Canada border.

The models continue to have large run to run and model to model
differences regarding a possible hurricane for the southeastern
United States early next week.

.AVIATION...for 06Z TAF Issuance
Issued at 1020 PM CDT Tue Aug 23 2016

An upper level disturbance was moving into western WI late this
evening. At the surface, a warm front was lifting north from
southern WI. These features were generating a large area of
showers and embedded thunderstorms over southeast MN, northeast IA
and west central/southwest WI. Low-level moisture was surging
toward the area, as evidenced by a large swath of MVFR ceilings to
our south.

The showers will be ongoing at AUW/CWA at the beginning of the TAF
period, and approaching the other TAF sites. The best chance of
concentrated thunderstorm activity should accompany the upper
disturbance as it moves through between 09z-15z/Weds, but showers
will linger into the afternoon. Ceilings and vsbys will
deteriorate rapidly overnight into Wednesday morning, with flight
conditions dropping to IFR at most locations. Ceilings will be
slow to improve, but VFR conditions should return to parts of the
forecast area during the late afternoon and early evening.

Beach Hazards Statement through Wednesday evening FOR WIZ022-040-


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