Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 181946
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
246 PM CDT Fri Aug 18 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Saturday
Issued at 245 PM CDT Fri Aug 18 2017

A short-wave trof will brush past the southern part of the
forecast area late this afternoon and evening, and bring
scattered light sprinkles to areas south of a line from
MFI-MTW. Clearing should occur later tonight as the upper trof
exits the region and weak high pressure arrives. This should
allow temperatures to drop into the 50s and lower 60s, and
lead to patchy fog development over much of north central
and central WI. The fog will be most prevalent in the favored
locations in north central WI.

On Saturday, a weak convergence zone will set up in the central
U.P. and far northeast WI, where CAPE is also forecast to increase
to around 1000 j/kg. Have added slight chance/chance pops in the
far northeast, especially over Door county. Otherwise, it will be
a pleasant summer day, with partly cloudy skies, warm temperatures
and comfortable humidity levels.

.LONG TERM...Saturday Night Through Friday
Issued at 245 PM CDT Fri Aug 18 2017

Zonal flow at 500mb will continue into early next week, then a
500mb ridge is expected to amplify across the Rockies with
northwest flow and depending trough across the Great Lakes region
during the middle to end of next week. Warmer than normal
temperatures are expected at the beginning of the period, then
should trend to or below normal for the latter half of next week.

Quiet conditions will continue Saturday night as high pressure
slides east of the area. Did make minor adjustments to low
temperatures to account for our typical cold spots. On Sunday,
a weak cold front will approach from the west. This system will
bring a chance of showers and thunderstorms to portions of north-
central and far northeast Wisconsin Sunday afternoon. The front is
expected to sink slowly southward across the area Sunday night,
bringing a chance of showers and thunderstorms to the entire
region. The system is expected to stall on Monday as the next
area of low pressure moves along the front and approaches
Wisconsin from the west. At this time, it appears that cloud
cover and the possibility of rain will spoil the solar eclipse
across the area.

Showers and thunderstorms are expected Monday night into Tuesday
morning as low pressure moves along the front. The rain should end
across eastern Wisconsin Tuesday afternoon as high pressure builds
into the region. Cool and dry conditions expected Tuesday night.
Latest model guidance is suggesting instability showers are
expected to develop across far northeast Wisconsin late Wednesday
morning into Wednesday afternoon. Have increase rain chances in
this area. Any showers should end around sunset. Otherwise, dry
and cool conditions expected Thursday and Friday.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1243 PM CDT Fri Aug 18 2017

Weakening cyclonic northwest flow and daytime heating will cause
MVFR ceilings to rise to VFR by 19z-20z. As low clouds erode,
they will likely be replaced by mid-level clouds associated with
a short-wave trof. This trof may produce a few light showers
or sprinkles in central WI in the late afternoon or early evening,
but will not mention any rain in the TAFs. Clearing is expected
to occur overnight, which should allow some fog to develop,
especially in the favored locations of north central WI. The fog
should mix out by 14z/Sat.
&&

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

$$

SHORT TERM.....Kieckbusch
LONG TERM......Eckberg
AVIATION.......Kieckbusch


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