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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA

FXUS61 KPBZ 030827

Area Forecast Discussion
National Weather Service Pittsburgh PA
427 AM EDT Mon Aug 3 2020

Rain chances will continue through Tuesday with persistent low
pressure over the region.


A large portion of the area will be in between the stalled trough to
the west and the atmospheric impacts surrounding TS Isaias to the
southeast, as it begins to move northeastward along the SE US coast.
Deep moisture to the north of the tropical low will interact with a
quasi-stationary front over VA. Being in this spot, most, if not
all, of the area will see an increase in large scale subsidence and
drier air. A large portion of the forecast area will remain rain free
with the best chance for showers on the western and northern edge of
the county warning area this afternoon. The far southeast ridges, in
WV and MD, could see a shower this afternoon, but most of the rain
in that neck of the woods will be confined to the aforementioned
front over the Mid-Atlantic region. Temperatures in the area of
subsidence will warm a few degrees from Sunday thanks to weak warm
advection and increased mixing with a decrease in mid clouds.


Models are not in great agreement with the overnight period. The
differences arise in how they are handling weak upper level energy
moving northeastward on the eastern flank of the crawling western
trough. Energy that does approach the area will weaken and be forced
northeastward in the tightening SW flow aloft. To find a happy
medium, included chance PoPs across the entire region tonight, but
the pattern suggests that most of the area will remain dry.

The upper trough axis will take all of Tuesday to make it through the
region and it will manage to push a weak a cold front through as it
passes. Improved rain chances can be expected Tuesday afternoon due
to the increase in large scale ascension and low-level forcing.
Models are also showing a destabilization of the atmosphere so an
isolated thunderstorm cannot be ruled out.

Subsidence will once again increase Tuesday night with all of the
attention well to our east-northeast as Isaias picks up speed and
moves through New England. Any lingering showers over the ridges will
end by midnight.

Wednesday setting up as a nice day with plenty of sunshine, seasonal
temperatures and comfortable conditions.


Flow aloft will weaken and become more zonal through the end of the
week, with sfc high pressure providing dry conditions for much of the
period. The exception could be a passing weak shortwave plus diurnal
heating and orographic lift across the ridges sparking isolated
storms each afternoon. Otherwise, rising heights and increased
insolation will see a warming trend into next weekend, with
temperature becoming above normal.


Lingering llvl moisture and clearing in eastern Ohio will create
spotty MVFR vis until dawn. IFR cigs will most likely linger near
FKL/DUJ; our special 06Z sounding has moisture elevated throughout
the boundary layer (sfc to 10kft). Areas under heavy restrictions
will improvement to VFR an hour or two after sunrise.

Isolated shra could develop west of PIT as a trof advances this
afternoon, but confidence is not high; swaths of mid level dry air
may advance into the Ohio River Valley. VFR will prevail until early
morning Tues. Some site restrictions (MVFR to IFR cigs) are
anticipated pre- dawn under spotty moist advection near the llvls.

Periodic restriction potential will be possible through mid week
under that persistent upper trof.





Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather