Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 191036
AFDGRB

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

Updated aviation portion for 12Z TAF 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 12Z TAF Issuance
Issued at 536 AM CDT Tue Sep 19 2017

Mainly VFR conditions expected today into tonight. The exceptions
may include a brief period of higher end MVFR cigs this morning
over parts of central and north central wisconsin, and then patchy
MVFR vsbys due to fog late tonight. There is a chance for showers
and storms late tonight over central and north central Wisconsin.
Low level wind shear conditions of SW winds to 40 knots at 2000
ft AGL may develop late tonight over parts of central and north
central Wisconsin. LLWS conditions may be approached at the end of
the taf period over eastern Wisconsion.
&&

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

$$

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


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