Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 271941
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
241 PM CDT Sat May 27 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Sunday
Issued at 241 PM CDT Sat May 27 2017

A line of showers developed late this morning/early this afternoon
and extended from Upper Michigan into far northeast Wisconsin in
an axis of surface moisture convergence coincident with elevated
instability.

The models had QPF in the general location of the current rain and
pretty much had it across the entire state during the day on
Sunday, though there were some differences in the exact location
and timing. Have PoPs increasing through Sunday as a mid level
short wave moves across Wisconsin and a surface boundary moves
into the state.

Temperatures tonight should only drop into the 50s due to
increasing clouds, precipitation, and dew points ranging from the
upper 40s to upper 50s. Clouds and rain will hold temperatures
down on Sunday but highs should still be in the upper 60s to
lower 70s at most inland locations.

.LONG TERM...Sunday Night Through Saturday
Issued at 241 PM CDT Sat May 27 2017

The main weather feature that will impact northeast WI continues
to be a closed upper low that is forecast to slowly move from
Ontario to Quebec during the better part of the upcoming week.
Several disturbances will move through the trof and enhance
precipitation chances from time-to-time.

Thanks to the vicinity of the upper low and general NW flow, temps
for most of the work week will be below norm more times than not,
especially in the first half of the week.

By the end of the work week, the upper low finally loses its grip
on the region`s weather and some flattening of the central U.S.
ridge follows per the ECMWF. While there are some differences
between the GFS and ECMWF with respect to the sharpness of the
upper ridge, temps should be a couple degrees warmer than the
early part of the week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1243 PM CDT Sat May 27 2017

VFR conditions prevailed across the forecast area at midday.
Models had some precipitation developing in far northeast
Wisconsin today, and there were some showers at 17Z in an axis of
moisture convergence and a small amount of elevated instability
in northeast Wisconsin ahead of a surface trough. Would expect
more development during the day, but did not mention
showers/thunder in the TAF during the day since the chances of
them impacting the TAF sites were not high enough. Potential for
showers and thunder increases significantly late tonight through
Sunday as a mid level short wave passes across the area and
another surface boundary moves across Wisconsin. Expect mainly
MVFR ceilings and visibility with some of the showers and storms.
Have left out any mention of thunder in TAFs but think there will
be some in the area, just not sure exactly where at this point.
&&

.MARINE...
Issued at 241 PM CDT Sat May 27 2017

Westerly winds, occasionally gusting to near 25 knots, are
expected on Memorial Day through Tuesday as low pressure meanders
across Ontario.
&&

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

$$

SHORT TERM.....MG
LONG TERM......JKL
AVIATION.......MG
MARINE.........JKL


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