Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 142354

Area Forecast Discussion
National Weather Service Green Bay WI
654 PM CDT Sat Oct 14 2017

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 325 PM CDT Sat Oct 14 2017

Showers moved into the southern part of the forecast area by
1930Z, reaching most locations south of Highway 29. The showers
are expected to spread across the rest of the area during the
evening and overnight hours as a surface low passes through
Wisconsin, followed by a mid level short wave trough. So far the
lightning detection network has shown no lightning anywhere in
Wisconsin. Would not rule out thunder since there is plenty of it
in upstream in Iowa and some elevated instability was evident on
Bufkit time/height plots. Would expect heavier rainfall this
evening and tonight as well.

Showers should exit the area on Sunday with some clearing in
central and north central Wisconsin during the afternoon. The
surface pressure gradient on the back side of the departing low
is expected to be rather tight, so winds across Door County will
probably reach wind advisory criteria on Sunday.

Lows tonight should be mainly in the 40 to 50 degree range. Cold
advection behind the departing surface system will bring cooler
high temperatures on Sunday. Readings should top out in the mid
40s to lower 50s.

.LONG TERM...Sunday Night Through Saturday
Issued at 325 PM CDT Sat Oct 14 2017

The upper trough that is forecast to move through
Sunday night will probably produce lake effect clouds across
northern Wisconsin with clearing across central Wisconsin. Frost
possible across central Wisconsin if skies are clear. Lows will be
in the low to mid 30s.

Pretty quiet weather is expected monday through Saturday with
mostly zonal flow and just a few weak shortwaves moving through
with little moisture. So dry and mild is what we are forecasting.

.AVIATION...for 00Z TAF Issuance
Issued at 644 PM CDT Sat Oct 14 2017

Flight conditions varied significantly across the region early
this evening, ranging from VFR in far northern WI to IFR/LIFR
in central and east central WI. Expect conditions to deteriorate
to IFR/LIFR across the entire forecast area tonight as periods of
rain saturate the lower levels of the atmosphere. There will be
two significant periods of rain during the period. The first will
move through the Fox Valley and Lakeshore areas this evening,
accompanied by a few thunderstorms. After a bit of a lull later
this evening into the early overnight hours, rain will increase
again from the west as a strong upper level trough moves through.
The rain will taper off during the mid to late morning as the
trough departs. Strong gusty northwest winds will develop as
low pressure departs and a cold front moves through late tonight
into Sunday morning, with gusts to 30 to 35 knots expected. Flight
conditions should improve during the morning, and return to VFR
in most locations by late morning or early afternoon.

Have added a period of LLWS to the RHI/AUW/CWA TAF sites this
evening, as east winds will crank up to 40 knots just off the

Issued at 325 PM CDT Sat Oct 14 2017

An intensifying area of low pressure will move through the region
tonight into Sunday morning.

East winds reaching small craft criteria may briefly diminish
this evening as the low moves across Wisconsin. As the surface
low departs later tonight, winds are forecast to rapidly shift to
the northwest and become gusty into Sunday. A period of gale force
gusts are expected from late tonight through Sunday afternoon when
a Gale Warning is in effect for the entire area.

Wind Advisory from 7 AM to 4 PM CDT Sunday for WIZ022.


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