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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 191738
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
138 PM EDT Wed Jul 19 2017

.SYNOPSIS...
Warm and humid weather will continue for the rest of the week.
Thunderstorm chances will escalate on Thursday and continue
periodically into the weekend as a series of disturbances
crosses the region.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
Quick update at 1:30pm for expanding coverage of showers.
Seeing showers developing in Washington, Marshall, and Muskingum
counties, and being unsure as to where else an isolated shower
might develop, have painted the area with slight chance showers.
Have still kept thunderstorm mention to locations north of
Interstate 80 and along the ridges, where there has been a
mention of precipitation throughout the day and still seems like
the most likely areas to receive any rain.

Previous...
Warmth (temperature about 5 degrees above average) and humidity
(dewpoints in the upper 60s/70) can be expected again today as
overall subsidence under ridging aloft is maintained between Mid
Atlantic States and Great Lakes troughing.

A slight chance for thunderstorms was introduced for the I 80
corridor and for the higher elevations as encroachment of a
couple weak shortwaves in conjunction with possible lake breeze
reinforcement and converged orographic flow may be sufficient to
penetrate the mid level warmth entrenched over the Upper
Allegheny region.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
A more substantial shortwave is progged across the northern
periphery of the Southern CONUS ridge on Thursday. That system
is expected to bring the next chance for thunderstorms to all
locations, and could pose a severe threat given the warmth,
humidity/resultant CAPE and improved mid level flow.

Models indicate a repetitive pattern for Friday and Saturday,
albeit with timing and track differences, so the general chance
PoPs were maintained along with ongoing warmth and humidity
given those differences and boundary placement questions.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
The pattern of shortwaves crossing in zonal/northwest flow is
expected to give way to Great Lakes-to-Northeastern-CONUS
troughing during the first half of next week. Warmth will thus
wane through the period as temperature moderates back toward,
and a few degrees under the average. Likely rain chances will
also diminish with dry weather projected by midweek.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
General VFR conditions forecast through the evening with
scattered-broken cumulus. Isolated showers/storms should remain
north of PIT, and handled with VCTS at FKL/DUJ. Tonight appears
a bit more favorable for fog, and have a period of MVFR/IFR at
most terminals. VFR after 13Z as fog lifts, with any organized
convection likely holding off until after 18Z.

.OUTLOOK...
Restrictions appear likely later Thursday afternoon and evening
with an organized line of convection. Additional rounds of
storms are expected through the weekend, and morning fog is
possible as well.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$