Area Forecast Discussion
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FXUS61 KPBZ 210419 AAC
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1219 AM EDT Mon Aug 21 2017

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

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A weak shortwave trough advancing out of the Midwest should
result in slight shower chances N of I 80 toward dawn, though
weak forcing a lack of deep layer moisture should limit this
potential. Otherwise, an increase in mid and high clouds is
expected ahead of the approaching trough. Lows are expected to
be a couple of degrees above average.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
That shortwave is the lead disturbance in a series of impulses
which will escalate rain chances into Tuesday. As for eclipse
viewing on Monday, local conditions are not looking as favorable
as previous as that lead impulse is expected to at least spawn
mid level cloudiness, and possibly some isolated convection with
its morning to early afternoon passage. The good news is that
at moment, weak shortwave ridging is timed to suppress precip
during the peak time of the event.

By Tuesday, strong low pressure is forecast to dig between the
James Bay and Great Lakes and pull a cold front toward the Ohio
Valley. Given model-world agreement, likely precip probabilities
have been maintained with ramped-up severe expectations as per
a strengthened pressure gradient and resultant wind profile. That
potential remains slight at moment as warm mid level temperature
will likely retard overall instability. Nevertheless, prudence
dictates inclusion in the Hazardous Weather Outlook, especially
in light of the projected boundary layer warmth and moisture.

Prefrontal trough passage is timed to end the severe threat by
Tuesday eve, with early Wednesday frontal passage heralding
cooler temperature for the remainder of the week.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Broad surface high pressure under high-amplitude Eastern CONUS
troughing is progged to support dry weather and sub average
temperature into the weekend.

&&

.AVIATION /04Z 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.

&&

$$



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