Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 300344
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1044 PM CDT MON AUG 29 2016

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 235 PM CDT Mon Aug 29 2016

The main forecast focus continues to be on precipitation chances
as a cold front slowly moves east across the Upper MS Valley/Great
Lakes over the next 24 hours.

The 19z MSAS surface analysis showed an area of high pressure over
Lower MI, a cold front extended from western Ontario southwest
through central MN to a weak area of low pressure over central SD.
Radar mosaic was generally quiet over WI this afternoon, other
than some chaff that moved into east-central WI.

Anticipate precipitation to remain sparse across the forecast area
this evening due to a lack of focusing mechanism. However, the
approach of the cold front toward central WI late tonight could
bring the next chance of showers and thunderstorms, especially to
north-central and central WI. Even with nocturnal cooling of the
atmosphere, the air mass remains unstable through the night, thus
thunder chances would be necessary although weak shear would
preclude any storms from becoming severe. Also expect to see more
fog for tonight, but amount of cloud cover will ultimately
determine how thick the fog can get. Another mild/muggy night on
tap with min temperatures in the middle 60s north, middle to upper
60s south.

The cold front is forecast to gradually push across the rest of
northeast WI on Tuesday. Air mass to remain warm, moist and
unstable with dew points in the middle 60s to around 70 degrees
with SBCAPES between 1500 and 2500 J/KG. Bulk shear values to
remain weak and with expected cloud cover overhead, this would
severely crimp any storm from turning severe. Therefore, have pops
accompanying the frontal passage with locally heavy rainfall and
brief gusty winds the main threat. Precipitation trends to
diminish from NW to SE in the afternoon with decreasing clouds for
the northwest half of WI. Max temperatures on Tuesday to range
from the middle to upper 70s north, to the lower to middle 80s
south.

.LONG TERM...Tuesday Night Through Monday
Issued at 235 PM CDT Mon Aug 29 2016

Ridging will build in across the western Great Lakes by the middle
of the week, bringing the first fall like temperatures to the
region. Temperatures by Thursday are forecast to fall a good 5
degrees below normal for this time of year with highs in the upper
60s to lower 70s. The next chance for rain could be on Thursday
across the lakeshore counties as models are generating some lake
effect rain showers across Lake Michigan. However not all model
solutions are generating these showers with the best convergence
offshore, therefore will continue with a dry forecast with this
issuance.

The high will provide for a long stretch of dry weather across
the region with rain not introduced back into the forecast until
Sunday. Even this return of precipitation is in question as the
long range models are hinting that the region may not get much in
the way of rain until later Sunday night or even into Monday.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1044 PM CDT Mon Aug 29 2016

Scattered Showers and Thunderstorms will arrive in north central
and central Wisconsin overnight. Elsewhere, ground fog is possible
later tonight, especially where skies are clear for awhile. IFR
ceilings and visibilities likely where fog materializes.

A weak cold front will move across the area Tuesday. It will be
accompanied by scattered showers and thunderstorms. VFR conditions
expected outside of convective activity.

&&

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

$$

SHORT TERM.....Kallas
LONG TERM......Kurimski
AVIATION.......RDM


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