Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 250540

Area Forecast Discussion
National Weather Service Pittsburgh PA
140 AM EDT Fri Sep 25 2020

Mostly dry and warm weather is expected through the weekend under
high pressure. Rain chances increase Sunday night through early next
week with the approach and passage of a cold front.


No changes needed for the evening update.

Previous discussion...
Surface ridging and a dry column will prevent precipitation across
the CWA. With little mixing overnight, patchy fog may form in valley
locations with less sky cover. Temperatures will remain a bit above


The surface ridge will continue to keep dry weather across most of
the region on Friday. Beta`s remnants will become absorbed by a
mid-level wave as it dips into the lower Ohio Valley. Most of the
deep moisture and right entrance region jet dynamics remain off to
our south. However, will continue to keep mentionable PoPs into
Friday evening in area southeast of I-68 that get skimmed by the
upper support, with low-level southeast flow perhaps adding an
upslope kick.

Mid and upper-level ridging will then build in Friday night and
linger through Saturday, with another round of dry weather.
Developing low-level SW flow and rising 500mb heights point to
continued warming during this period, with temperatures of 5 to 10
degrees above seasonable levels projected.


A mostly dry and warm Sunday is still projected as central CONUS
troughing remains slow to develop, leaving southerly flow in place
for our area. Many locations should reach or top the 80 degree level
that afternoon - possibly for the final time of the season.

A shortwave rotating around the base of the developing trough will
bring a chance of scattered showers to most locations Sunday night
into Monday. This would be the first measurable rain in nearly two
weeks for much of the region. Ensembles continue to show that the
trough will then deepen and impact the eastern CONUS through the
remainder of next week. This will bring occasional shower chances and
below-normal temperatures from Tuesday onward.


Latest satellite imagery shows valley fog beginning to develop and
expand across the area. Most terminals should see fog by dawn, with
IFR/LIFR vsbys likely. Fog will quickly dissipate after sunrise once
near-surface mixing commences.

Otherwise, VFR conditions will prevail through the remainder of the
TAF period with a light southeast wind.

With the exception of pre-dawn fog; VFR is expected through Sat
under high pres.




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