Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 242335
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
635 PM CDT TUE MAY 24 2016

Updated aviation portion for 00Z TAF issuance

.SYNOPSIS...
Issued at 238 PM CDT Tue May 24 2016

A much wetter weather pattern is settling in over the area.

The sharp upper ridge which brought a prolonged period of very
dry conditions to the area is now to our east, while an upstream
trough is located over the southwest United States. Southwest
upper flow between these features has become established across
the forecast area, and is likely to remain in place throughout the
forecast period.

The newly established pattern favors much wetter weather than it`s
predecessor. Though timing remains in doubt, several rounds of
showers and thunderstorms are likely during the period--resulting
in above normal precipitation. Daytime temperatures will vary
between normal and above normal depending on the amount of clouds
and precipitation. The increased humidity will keep overnight lows
well above normal.
&&

.SHORT TERM...Tonight and Wednesday
Issued at 238 PM CDT Tue May 24 2016

Scattered showers and isolated thunderstorms continued across
north-central and northeast Wisconsin this afternoon. Some of
the stronger storms were producing gusty winds, locally heavy
rainfall and small hail.

A weak surface front will drop southward across the area late
this afternoon and tonight. Scattered showers and isolated
thunderstorms will come to an end this evening across much of the
area. Left a lingering chance of showers after midnight across the
south with the passage of the front. With 35 to 45 knots of wind
shear, still some heating of the day and boundary dropping south,
did not feel comfortable in removing the possibility of an
isolated severe storm.

For Wednesday, main problem is timing the arrival of the next
chance of showers and thunderstorms. Have trended slower from
previous forecast, but the midnight shift may need to slow it
down even more. High temperatures will again be on the warm side
if the rain arrives later in the day. The only exception will
be across eastern Wisconsin near Lake Michigan where an easterly
wind will keep it cooler. Not expecting any severe weather on
Wednesday.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 238 PM CDT Tue May 24 2016

Long-term forecast challenges continue to be the specifics of the
precipitation chances, and the risk of severe weather.

Typical forecast issues with southwest flow continue today.
Confidence is high that it is going to rain at times, and that
significant rainfalls will occur. But the details of when it will
rain remain elusive. Will continue to carry chance-likely PoPs
throughout the long-term portion of the forecast and hope we can
add additional resolution as each day shifts in the short-term
part of the forecast. Expect widespread 1 to 2 inch rainfalls
across the area during the next week, with some locations probably
getting over 3 inches.

The air mass across the area will become increasingly unstable as
gulf moisture arrives in the area. A marginal/limited severe
threat could develop during almost any of the long-term forecast
periods depending on the position of the main frontal boundary and
small scale shortwaves riding northeast in the upper flow. Much of
the medium range guidance shows a somewhat stronger/larger scale
shortwave crossing the region during the first half of the
upcoming weekend. If that feature evolves as now shown on the
guidance, it could lead to a more substantial risk for severe
weather when it arrives. Of course, that is still several days
away and a lot can change between now and then.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 635 PM CDT Tue May 24 2016

isolated showers or thunderstorms possible through
sunset...otherwise vfr expected through the early morning hours.
a weak cold front will move south across the region late tonight
and winds will shift to the east after it goes by. moist air
blowing over the cool lake waters may produce ifr ceilings and
visibilities at mtw/sue/grb/atw/osh from around 09z through 14z.
some low clouds are also possible across northcentral wisconsin.
wednesday should have dry weather through early afternoon...then
showers and thunderstorms will arrive during the late afternoon
from southwest to northeast.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Eckberg
LONG TERM......Skowronski
AVIATION.......RDM



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