Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 271803

Area Forecast Discussion
National Weather Service Green Bay WI
103 PM CDT WED JUL 27 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 215 AM CDT Wed Jul 27 2016

Forecast issue will be coverage and timing of convection today
into Thursday. Primary mechanisms for convection will be
associated with a cold front slowly dropping into northern
Wisconsin this morning and an approaching short wave trough
centered over west central minnesota early this morning.

Early this morning, convection over far northeast wisconsin
likely being enhanced in the RRQ region of the upper jet.
meanwhile convection approaching northwest or west central
wisconsin associated with the approaching short wave.

Progs slowly drop this front southward over the region today into
Tonight while the short wave also slowly drifts eastward into the
state today into tonight. Due to overnight convection and weak
flow, difficult to locate the surface boundary but convection so
far near the 850 front currently just north of the state early
this morning.

As far as severe weather, the air mass will be moderately
unstable today as the 850 warm prod drifts south. Clouds could be
a limiting factor with shear on the weak side. Locally heavy
rainfall may be the primary concern as pwats climb to 1.50 inches.
While these pwat values normally would not indicate heavy rain
alone, the slow movement of the cold front and short wave trough
will likely also produce slow storm movement. Will highlight the
heavy rain concern in the hwo.

Trend of models is a bit quicker departure of the front to the
south Thursday and a north to south diminishing trend of the

.LONG TERM...Thursday Night Through Tuesday
Issued at 215 AM CDT Wed Jul 27 2016

A mainly dry and cooler stretch of weather late in the week into
the weekend as high pressure builds into the area under a weak
northwest upper flow.

Canadian high pressure will continue to sag south over the Great
Lakes region Thursday night in the wake of a cold front retreating
to the south. Some progs suggest a few showers may linger thursday
evening over areas south of highway 10, but will continue with the
drying trend.

Progs are generating spotty light precipitation this weekend over
mainly east central wisconsin toward Lake Michigan due to weak
upper troughing drifting over lower Great Lakes region. An upper
ridge builds over the area late this weekend into next week.
Return flow on the backside of the high will lift the very warm
humid air mass just to the south back northward into the area
again. The next chance of rain will be toward Tuesday with the
passage of a cold front and short wave trough passing over the
northern Great Lakes region.

.AVIATION...for 18Z TAF Issuance
Issued at 102 PM CDT Wed Jul 27 2016

A cold front dropping slowly south across WI will produce showers
and thunderstorms at times this afternoon and tonight. VFR
ceilings and visibilities expected outside of any precipitation
this afternoon and evening but MVFR conditions expected late
tonight and early Thursday.




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