Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 132348
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
648 PM CDT Fri Oct 13 2017

Updated aviation portion for 00Z TAF issuance

.SYNOPSIS...
Issued at 245 PM CDT Fri Oct 13 2017

Wet, windy, and turning briefly colder this weekend, then mild
and quiet weather to return next week.

The amplified upper flow across North America will flatten the
next several days as the bulk of the energy within a western
longwave trough ejects eastward. The resulting energetic but
zonal regime of early next week will gradually amplify later in
the week, with a trough once again forming near the West Coast
and downstream ridging over central and eastern NOAM.

Daily temperatures will vary between near and modestly above
normal throughout the period. Precipitation amounts are likely to
end up AOA normal, with the primary precipitation producer being
the cyclone that crosses the region this weekend. The prospect for
significant precipitation during the remainder of the period
appears low.
&&

.SHORT TERM...Tonight and Saturday
Issued at 245 PM CDT Fri Oct 13 2017

The main short-term forecast issue is the timing of rain chances
with the initial wave crossing the area this evening, and the
arrival of the main system tomorrow. Overall, the models were in
pretty good agreement, though the NAM and hi-res WRFs were
considerably slower with the northward push of rain ahead of the
primary cyclone tomorrow. Trended the forecast toward the
majority, but held PoPs across the north back until late in the
day in case the NAM/WRFs are onto something.

Stayed with a limited diurnal temperature range for most areas.
But given the likelihood of a period with mostly clear skies and
light winds across the north tonight, lowered mins there toward
the min of the distribution of guidance low temperatures.

.LONG TERM...Saturday Night Through Friday
Issued at 245 PM CDT Fri Oct 13 2017

Low pressure will move from southeast Colorado to southern Lake
Michigan Saturday through Saturday night, as an upper trough moves
across the central plains to the Great lakes. The system doesn`t
seem quite as dynamic as it did yesterday, but is still strong
enough to bring significant rain and a few thunderstorms. Rainfall
amounts of an inch or so are possible.

The surface low intensifies quickly as it moves from southern Lake
Michigan Saturday evening to western Quebec, producing a strong
pressure gradient that will produce gusty northwest winds Sunday.
The rain should end early Sunday as the surface system exits the
area. Blustery and cool weather is expected Sunday afternoon.

The 500mb flow is forecast to become nearly zonal Tuesday through
Friday, which should result in dry and mild weather for
Wisconsin.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 639 PM CDT Fri Oct 13 2017

VFR conditions were observed across much of north central,
central and far northeast WI early this evening. Rain and low
clouds should continue to edge southeast across the Fox Valley
and lakeshore areas during the evening as a cold front moves
through and the leading edge of drier air arrives. The improving
conditions will be temporary, as rain and lowering ceilings will
return to central and east central WI in the late morning and
early afternoon on Saturday, then spread into northern WI later
in the day. Flight conditions will deteriorate to IFR at
GRB/ATW/MTW during the mid to late afternoon as the rain
intensifies.
&&

.MARINE...
Issued at 245 PM CDT Fri Oct 13 2017

An intensifying area of low pressure will move through the
region Saturday night into Sunday morning. Initially, east winds
are expected to increase Saturday afternoon with waves approaching
small craft advisory criteria (4 ft) on Lake MI. The winds may
briefly diminish Saturday evening as low pressure moves across
Wisconsin. As the surface low departs later Saturday night, winds
are forecast to rapidly shift to the northwest and become gusty
into Sunday. A period of gale force gusts are possible from late
Saturday night through Sunday afternoon.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......RDM
AVIATION.......Kieckbusch
MARINE.........RDM



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