Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 201952
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
252 PM CDT Tue Jun 20 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Wednesday
Issued at 252 PM CDT Tue Jun 20 2017

Scattered showers and isolated thunderstorms will come to an end
late this afternoon or early this evening. Some of the showers and
storms could still produce some gusty winds to 35 mph, brief heavy
rain and small hail. Clouds should be on the decrease later this
evening with mostly clear skies expected overnight into Wednesday
morning. Some patchy fog is possible late tonight across much of
the area.

Any fog should burn off by 8 or 9 am. Clouds will be on the
increase by late morning as fair weather cumulus clouds should
develop and continue through the afternoon. By late afternoon,
low level jet is expected to crank up across Iowa and pointed
towards the area. Models differ with the onset of convection.
Most of the models have showers and storms arriving after 7 pm
Wednesday, except the ECMWF. Have added a small chance (20%)
across our southwest counties after 5 pm on Wednesday to account
for the quicker ECMWF model.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 252 PM CDT Tue Jun 20 2017

Showers and thunderstorms will spread over the area Wednesday
night with a developing low level jet to 40 knots working into the
region. Deep layer shear develops as the upper jets slides over
the area. Much of the area is in a Marginal risk threat, with the
slight risk area just to the southwest within the area of greater
instability.  Trend of the progs is to slow down the cold front
Late Wednesday night into Thursday night as the upper flow
becomes more west to east. The greatest threat of strong storms
Thursday will be over the southern portion of the state near the
greatest instability and frontal location, but close to parts of
central and east central Wisconsin.

Progs drop the front further south on Friday but some progs do drop
a northern stream trough into northern Wisconsin for a chance
of a diurnal type convection.

Otherwise the pattern this upcoming weekend and early next week
indicates more chances of rain as an upper trough settles over
the Great Lakes region, with again mainly afternoon instability
type of convection with MU cape values peaking in the afternoons.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1210 PM CDT Tue Jun 20 2017

Scattered showers and a few thunderstorms will come to an end
later this afternoon or early this evening, mainly across
northeast and east-central Wisconsin. High pressure will bring
clear skies during the late evening and overnight hours. Latest
numerical guidance would not suggest any fog tonight, but the
combination of clear skies and light winds would allow for some
patchy fog to develop. Any fog should burn off by 13z on
Wednesday. Attention then turns to another complex of
thunderstorms that should arrive late Wednesday afternoon or more
likely Wednesday evening across central Wisconsin, then move
across northeast Wisconsin later Wednesday evening into early
Thursday morning. Strong to severe thunderstorms with large hail
or strong damaging winds are possible. Stay tuned!.
&&

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

$$

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



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