Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 270758

Area Forecast Discussion
National Weather Service Pittsburgh PA
358 AM EDT Tue Jul 27 2021

Crossing upper level waves may spark a shower or storm across mainly
northern areas late today and overnight. A Thursday cold front will
bring a better chance for widespread showers and storms.


Northwest flow aloft will keep its hold on the area today. A much
drier airmass has settled in over the region and will stay in place
today. A weak, moisture starved, shortwave trough will cross the area
this afternoon. With the lack of deep moisture, this wave will do
little except perhaps bring an increase in cu to the north.

With plenty of sunshine today, and surface dewpoints remaining more
tolerable, temperatures will push well into the 80s with urban
locales approaching 90 degrees.


A more extensive trough will quickly cross the area this evening.
Seeing some difference with the model solutions on how they handle
the impacts from this wave. The differences come in the strength of
the wave and how far south the deeper moisture intrudes. Most of the
data is pointing to a drier forecast with the deepest moisture
remaining north of the region. Any activity tonight looks to be
isolated and mainly over the I-80 corridor.

The trough will pull a weak surface boundary southward late tonight
which will slowly cross the region on Wednesday. With a lack of upper
level support and moisture, it appears any activity Wednesday would
again be isolated and centered along the crossing front.

Best support for precipitation will come Thursday as the nose of an
upper level jet and mid-level shortwave advance ahead of the cold
front. However, at this time, there is low confidence in the
Thursday forecast due to pretty substantial timing and support
differences in the model data.

Temperatures will remain above average through the period.


West-Central CONUS ridge will remain in place through the weekend as
several shortwaves dig the trough in the east. Focus for
precipitation will generally remain north of the Ohio valley with
shortwave ridging keeping conditions dry and seasonably cool for much
of the weekend.


High pres wl maintain VFR with exception for lcl peri-dawn fog.
Expect some increasing mid level clouds into the afternoon with light
winds and continued VFR.

The next best chc for genl restrictions and likely rain will be with
a Thu cdfnt.




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