Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 211104

Area Forecast Discussion
National Weather Service Green Bay WI
604 AM CDT Sun May 21 2017

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 405 AM CDT Sun May 21 2017

Closed upper low will lift northeast across northwest Wisconsin
today. The last significant upper forcing will produce a broken
line of showers and thunderstorms early this morning. Some wrap
around showers are possible across the northwest part of the
forecast area this afternoon. Low clouds and areas of fog will
dissipate as a surface front swings by and winds shift to the
southwest. Highs today will be close to normal in the east and 5
to 10 degrees below normal in the west where cold advection will

Cyclonic upper flow will keep cloudy skies over the region tonight
with scatterd showers possible mostly north and west of the lake
and bay. Lows will be close to normal.

An upper trough will approach the area from the north Monday, while
jet energy also approaches from the central Plains. They should
combine to produce some showers especially in the afternoon.

.LONG TERM...Monday Night Through Saturday
Issued at 405 AM CDT Sun May 21 2017

Precipitation chances and timing remain the primary forecast
concerns during this part of the forecast.

Cyclonic flow aloft and a surface low moving northeast along a
cold front will bring chances for showers to the area Monday
night, with the highest PoPs in the eastern and southern parts of
the area. There could also be some thunder across parts of central
and east central Wisconsin Monday evening due to lingering surface
based instability. The chance for showers increases across most of
the area for Tuesday and Tuesday night as a 500 mb low passes
through Wisconsin. Rain chances gradually end from west to east on
Wednesday with the arrival of surface high pressure and a mid
level ridge. Another surface low and mid level short wave trough
approach the region later in the week, but there are only slight
chance PoPs starting Friday night due to differences in model QPF

Clouds and precipitation across the area will result in rather
cool daytime temperatures through Wednesday. Southerly flow ahead
of the approaching system is expected to bring warmer air and
high temperatures near normal from Thursday into the weekend.

.AVIATION...for 12Z TAF Issuance
Issued at 604 AM CDT Sun May 21 2017

Low clouds and IFR conditions will likely improve to
MVFR during the afternoon over all but northcentral Wisconsin.
Scattered thunderstorms ahead of a weak frontal system will exit
by 15z with just scattered showers across central and northcentral
Wisconsin this afternoon and tonight.

Drier air will arrive Monday, which will help conditions to rise
into VFR range in most places by midday.



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