Area Forecast Discussion
Issued by NWS Green Bay, WI

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714
FXUS63 KGRB 210327
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1027 PM CDT Tue Aug 20 2019

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Wednesday
Issued at 213 PM CDT Tue Aug 20 2019

Skies were mostly cloudy across the region this afternoon.
Temperatures were in the lower to middle 70s across central
and north-central Wisconsin to around 80 across northeast
and east-central Wisconsin.

For tonight, a cold front will drop south across the area.
This feature will bring a small chance of showers and
thunderstorms as it moves across the area. A few stronger
storms are possible late this afternoon and early this
evening across central and north-central Wisconsin.
Shear values of 25 to 35 knots noted along with
CAPE values of 1,000 to 1,5000 J/KG. Main risk would be
gusty winds and small hail. The chances of showers and
storms will end from northwest to southeast tonight, ending
across eastern Wisconsin after midnight. Late tonight, there
may be a band of low clouds that drop south along with some
patchy fog north and west of the Fox Valley.

Any fog should burn off by mid-morning on Wednesday. Partly
cloudy skies will prevail with highs in the 70s. Dewpoint
readings will be in the 40s north and in the upper 40s to
middle 50s south tomorrow afternoon.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 213 PM CDT Tue Aug 20 2019

The long term period will be largely dominated by a passing upper
level ridge, and the next trough moving through by the end of the
weekend.

Thursday, a fairly prominent upper level trough will pass over the
region, bringing rain and storms south of the area in the
afternoon and evening. The GFS/ECMWF have begun to hint that a
few showers may be possible across east-central WI and the
southern Fox Valley in the afternoon, but with the lack of
moisture and instability, stuck with the drier guidance for this
issuance.

Thursday night, high pressure will dominate the region as the
upper level ridge moves in. Northerly flow will bring much colder
air into the region. Winds near calm by Friday morning could allow
the north-central cool spots to drop quickly before sunrise.
Therefore went with the coolest guidance for the area, and
temperatures in the middle 30s for the lows for the north.

High pressure will then dominate the region through Saturday
night, keeping the area dry. Return flow on the west side of the
high will gradually bring in warmer temperatures again on
Saturday.

The speed the ridge moves through will largely dictate how
quickly precipitation moves in Sunday into Monday. Currently, a
slowly deepening upper level trough is expected to develop and
move across Minnesota Saturday night into Sunday morning. Guidance
then remains a bit unclear as to how quickly this feature will
bring pops into central Wisconsin. Kept a few chances in by the
early portion of the day. A surface low is expected to develop
with the upper level feature and deepen on Sunday, before
progressing eastwards across the area by Sunday night. The low
then lingers on into Monday. This will be the best chance to see
storms develop in the extended period, but it`s still too early to
determine any severe potential.

Temperatures will be below normal through Friday, then rise back
up to near normal by Monday and Tuesday.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1027 PM CDT Tue Aug 20 2019

A cold front moving across the area overnight may produce a few
brief showers and MVFR conditions. The front will exit the region
around daybreak, with VFR conditions expected Wednesday and Wednesday
night with mostly clear skies and excellent visibility.

&&

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

$$

SHORT TERM.....Eckberg
LONG TERM......Uhlmann
AVIATION.......RDM



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