Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 242326

Area Forecast Discussion
National Weather Service Green Bay WI
626 PM CDT Mon Jul 24 2017

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 234 PM CDT Mon Jul 24 2017

High pressure drifting over the Great Lakes Region this afternoon
through tuesday will bring cool comfortable and quiet conditions
to the area.

Winds turn to the south on Tuesday, any warming may be offset with
increasing mid to high level clouds with an approaching frontal
and upper trough from the Northern Plains.

.LONG TERM...Tuesday Night Through Monday
Issued at 234 PM CDT Mon Jul 24 2017

An active pattern is anticipated through Wednesday night which is
the focus of this forecast period. A quieter regime of weather is
then expected for the remainder of the work week and into much of
the weekend.

Satellite WV loop this afternoon shows 2 short wave troughs to
the west, one over the Dakotas and producing scattered
convection, and the primary deeper upper trough north of the
montana/canadian border. High level clouds from the first system
may reach parts of western Wisconsin tonight. Otherwise progs
phase these systems through Tuesday and move a diffluent flow
aloft region into the northwest half of the state Tuesday
afternoon. Anticipate the dry surface high will keep the area
dry but clouds may be on the increase.

Best instability develops Tuesday afternoon into Tuesday night
over Minnesota. Increasing westerly winds aloft will tend to
direct convection into the north half of the state overnight which
includes north central and central Wisconsin. The cold front is
progged to reach the DLH around or shortly after midnight Tuesday
night. Available soundings indicate some capping over the forecast
area but mid level lapse rates progged to be the increase
overnight into Wednesday morning as the 850 temperatures are on
the increase ahead of the front. Progged MU capes taper off
a bit Wednesday morning, while pwats increase to around 2.00
inches across the area due to convergence along the nearly west
to east frontal boundary. Location of this frontal boundary for
Wednesday will likely be a continued focus of heavier rainfall if
storms and showers train.

Not confident of severe weather occurrence Wed morning due to a
lag of mu capes, but the potential increases in the afternoon as
the best instability builds over the south half of the state ahead
of the frontal boundary, including parts of central and east
central Wisconsin. In addition to the instability, mid level winds
and deep layer shear increase as the primary short wave trough
slides across the northern Great Lakes Region. Convection
Wednesday night will tend to linger until this short deep upper
trough slides enough northeast of the area to allow the upper flow
to turn more northwest and push the front and convection
south of the area.

In the wake of the cold front Wednesday night, high pressure to
then settle into the area for the remainder of the work week and
into the weekend. Upper heights continue to build over the
northern plains next weekend resulting in a northwest flow over
the area. Some progs drop a weak short wave over the area on
Sunday for a chance of showers or storms.

.AVIATION...for 00Z TAF Issuance
Issued at 625 PM CDT Mon Jul 24 2017

High pressure will be over the region tonight, with only
cirrus invading from the west.  Fog potential looks too patchy to
include in the tafs. As the high departs on Tuesday, increasing
southerly winds will draw in more moisture, resulting in scattered
cu formation by late morning to early afternoon.

Beach Hazards Statement until 7 PM CDT this evening for WIZ040-


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