Monday, August 21, 2017, 7:58 AM EDT
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Area Forecast Discussion
||Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 211104
Area Forecast Discussion
National Weather Service Pittsburgh PA
704 AM EDT Mon Aug 21 2017
A weak upper level trough has returned low rain chances to the
forecast today. Widespread showers and thunderstorms are
expected with the approach and passage of a Tuesday cold front.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The dawn update included some adjustments to POPs in the form of
a slight convection chance with the shortwave emerging from the
midwest. High res models do indicate ongoing showers over Ohio
will fade, but cannot rule out an isolated occurrence with the
advance/passage of that system, especially with the increasing
warmth and humidity in the boundary layer.
Otherwise, an increase in mid and high level cloudiness is likely
to mar the eclipse viewing, although a brief period of shortwave
ridging may save the "peak" time of the event. High temperature
is expected to be around 5 degrees above the seasonal average.
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
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.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Broad surface high pressure under Eastern CONUS troughing is
progged to support dry and cooler than average weather through
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
General VFR is expected for the period although a crossing
shortwave may spawn some isold, to sct convection. Expect rapid
deterioration of conditions on Tuesday as widespread precip will
herald the advance of cold front.
With passage of an early Wed cold front, general VFR can be
expected for the remainder of the week.