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000
FXUS61 KPBZ 210700
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
300 AM EDT Mon Aug 21 2017

.SYNOPSIS...
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A weak upper level trough will return slight rain chances to
the forecast today. Widespread showers and thunderstorms are
expected with the approach and passage of a cold front Tuesday
and Tuesday night.
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&&

.NEAR TERM /THROUGH TODAY/...
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A weak shortwave trough advancing out of the Midwest should
result in slight shower chances mainly N of I 80 early this
morning, though weak forcing a lack of deep layer moisture
should limit this potential.

A period of weak shortwave ridging is expected after the wave
exits by early afternoon, though patchy mid/high clouds could
at least somewhat mar eclipse viewing. Isolated thunderstorms
are possible by late afternoon as the ridging flattens and
convective temps are reached. Temperatures are expected to be
around 5 degrees above the seasonal average.
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&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
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Isolated thunderstorms are possible this evening, though these
should diminish with waning instability after sunset.

By Tuesday, strong low pressure is forecast to track across the
Great Lakes, pulling a cold front toward the Ohio Valley.
Showers and thunderstorms are expected as the front approaches,
and as a pre frontal trough tracks across the area. Model
progged wind/shear profiles look favorable for a damaging wind
potential with the storms, though warm mid levels could
initially limit instability. SPC`s slight risk/sct coverage
outlook for severe storms seems reasonable at this time, and
will continue to include in the Hazardous Weather Outlook.
Outside of any storms, a tightening pressure gradient and mixing
could result in 25-30 mph wind gusts.

The pre frontal trough passage is timed to end the severe
threat by Tuesday eve, with early Wednesday frontal passage
heralding cooler temperatures. Building sfc high pressure under
broad should maintain the dry and cool weather Wed night.
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&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
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Broad surface high pressure under Eastern CONUS troughing is
progged to support dry and cooler than average weather through
the period.
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&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
High pressure will provide prevailing VFR conditions through the
period. A brief period of pre-dawn MVFR fog is possible at
southern ports.

.Outlook...
Widespread restriction potential returns with a late Tue/early
Wed cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$

07/22