Area Forecast Discussion
Issued by NWS Green Bay, WI

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710
FXUS63 KGRB 190800
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
300 AM CDT Tue Sep 19 2017

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 300 AM CDT Tue Sep 19 2017

A weak mid level short wave will continue to slide northeast of
the area this morning to diminish or end the isold showers.
Showers were also aided by mid level warm air advection ahead of a
deeper trough dropping into the Northern Plains today into this
evening. Showers and storms will be on the increase from west to
east tonight with the increasing LLJ ahead of the northern plains
trough and cold front.

The cold front passage arrives Wednesday with continued chances of
showers and storms. Due to ideal timing of the cold front in the
afternoon and evening, some potential for strong to severe storms.
MU cape values reach 1500 J/kg above an eroding cap in the
afternoon over eastern Wisconsin. Total totals climb into the mid
50s early evening over eastern WI. Shear values range from 30-40
kt shear, with a brief period of a deeper layer shear in the
evening as the upper jets lifts northward over the Northern Plains
and far northeast area of the Great Lakes.

Southeast surface winds will keep lake michigan temperatures in
check but above normal temperatures continue today with some
slightly cooler readings for Wednesday due to more clouds and
convection.

.LONG TERM...Wednesday Night Through Monday
Issued at 300 AM CDT Tue Sep 19 2017

The lack of warmth in August will be made up this week with
temperatures by the weekend some 10 to 20 degrees above normal.
Temperatures early next week will return closer to seasonal
normal which by this time will be in the middle to upper 60s.

Several chances of thunderstorms are in the forecast. A cold
front moving across the region Wednesday afternoon evening
will trigger scattered thunderstorms. A few of these storms
could be strong or possibly severe into early Wednesday evening.
The cold front will clear the area by later Wednesday night,
bringing an end to the rain. High pressure will move across
the region on Thursday. Return flow on the backside of the
high pressure system may trigger a shower or thunderstorm
across the far north Wednesday night, thus warranting a
small chance of rain.

The next chance of showers and thunderstorms will be on Sunday
into Monday. Low confidence in the chance of showers and storms
on Sunday, as hurricanes Jose and Maria spin off the east coast
of the United States. This scenario will probably slow down the
weather pattern until the move away from the United States.

The main story will be the increasing heat and humidity by the
end of the week into next weekend. Highs Friday through Sunday
will be in the 80s, with a few locations approaching 90 on Friday
and Saturday. Temperatures will return closer to normal early next
week.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1103 PM CDT Mon Sep 18 2017

Radar trends last few hours has indicated areal coverage of light
shower activity has been diminishing steadily. Short-term model
guidance suggests only isolated light showers or sprinkles will
remain by over eastern Wisconsin for the remainder of tonight as
weak upper-level impulse moves away from the area. Although
ceilings will generally remain in the VFR category, some areas of
MVFR cigs are possible especially over central Wisconsin where
light precipitation was a bit more widespread earlier this evening.
However, confidence was not high enough to go below VFR after
midnight for this issuance given current rapid decay of light
precipitation. Generally VFR conditions on Tuesday as weak upper
ridging commences downstream of robust shortwave trough
approaching the intermountain west.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......Eckberg
AVIATION.......ESB



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