Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 180920

Area Forecast Discussion
National Weather Service Green Bay WI
420 AM CDT Thu May 18 2017

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Friday
Issued at 418 AM CDT Thu May 18 2017

The unseasonably strong upper system that produced severe thunderstorms
across parts of the area yesterday afternoon and evening will weaken
as it moves off into the upper ridge over the northeastern United
States. As it does so, the surface system will quickly exit bringing
the showers to an end during the afternoon hours. Heavy rain is possible
for awhile this morning across the far north. It will turn much colder
from north to south today as the cold front goes by, with steady or
falling temperatures in most areas.

Surface high pressure will build in quickly tonight as a an upper
ridge approaches from the west. The models forecast very dry air
to accompany the high, with precipitable water values of .15 to .25
inches being near record low values for this time of the year. With
a cold start to the evening and clearing skies, temperatures should
fall quickly in central and northcentral Wisconsin, with freezing
temperatures possible. A frost advisory or freeze warning may be
issued later today. A frost is not likely across eastern Wisconsin
where winds will be slow to diminish and the warmth of the lake
and bay will keep temperatures around 40F.

Friday looks to be dry until late in the day. Increasing clouds
will hold temperatures about 5 to 10 degrees below normal.

.LONG TERM...Friday Night Through Wednesday
Issued at 418 AM CDT Thu May 18 2017

A return to southerly flow aloft and a surface low approaching the
state from the southwest will bring warmer temperatures and wet
weather back to the area.

Daytime high temperatures are expected to gradually warm to near
normal by Monday, before cooler air moves in behind a passing up
upper level trough.

There is a chance for showers starting Friday night, ahead of the
approaching surface low. Thunderstorms are possible Saturday
afternoon and evening. Rain chances drop off after Saturday night
with the arrival of the dry slot. Model QPF fields vary, so there
are mainly just slight chance PoPs through the early part of next

.AVIATION...for 06Z TAF Issuance
Issued at 1207 AM CDT Thu May 18 2017

Lower ceilings will gradually develop southward through the area
tonight. Anticipate primarily MVFR, though some brief IFR ceilings
are possible in the north. Expect MVFR ceilings in the wake of the
cold front tomorrow, before clearing trend start late in the
day/during the evening.



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