Hidden Valley (PA)

000
FXUS61 KPBZ 281128
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
728 AM EDT Tue Jul 28 2026

.WHAT HAS CHANGED...
Messaging remains similar but focused on incoming shortwave and
its thunderstorm development featuring marginal severe risks.

&&

.KEY MESSAGES...
1) Thunderstorms overspread the region this morning, featuring
limited wind and flash flood risks.

2) West to east tapering of precipitation chances tonight 
through Wednesday.

&&

.DISCUSSION...
KEY MESSAGE 1...
Latest analysis shows the surface low centered just north of
Toronto, Canada with the mid-level shortwave diving SE out of
northern MI. This is resulting in warm front induced scattered
thunderstorms firing in northwest PA (mostly into CTP's forecast
area) while growing storm coverage approaches eastern OH ahead
of the mid-level wave and surface front.

Confidence is fairly high in the shortwave and pre-frontal
trough traversing SE through 12z/8am to kick off mostly 
elevated thunderstorms tapping 1000-1500 J/kg MUCAPE. The lack 
of surface based storms and stronger buoyancy should limit 
severe potential but risks are non-zero thanks to near 1000 J/kg
DCAPE that could foster strong enough descending air associated
with the most organized cells to result in localized damaging 
winds. Increasing effective shear with the shortwave may also 
allow for enough updraft organization/maintenance to foster 
isolated instances of large hail. The biggest caveat is the 
likely southward path the cluster is favored to take by hi-res 
models, meaning far eastern OH zones are the most at-risk for 
this round of storm risks; areas east are likely to see more
stratiform region rain showers and/or cloud cover the initially
inhibits additional convective activity.

Though the shortwave exits by 14z, additional lift offered in
cooler NW flow plus the cross surface cold front should result
in additional afternoon convection mainly east of I-77. Buoyancy
may recover near 1000 J/kg with enough DCAPE available to
maintain a damaging wind threat, assuming enough clearing in
clouds occurs prior to frontal passage (not a given). Loss of
diurnal heating and waning upper support results in dwindling
storm activity after 21z tonight, with all risks tapering off by
00z.

KEY MESSAGE 2...
The upper pattern features a closed upper trough meandering over
the New England region late tonight through Thursday. Weak
shortwave movement around this low plus wrap-around moisture
could foster isolated to scattered diurnal storms Wednesday
(east of I-77) and Thursday (mainly along higher terrain) in
what otherwise would be a drying period with slowly building
high pressure.

These storms are unlikely to pose risks due to limited
instability (less than 500 J/kg).

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
An initial area of showers and thunderstorms will continue to
exit the region early this morning along a pre frontal trough. 

Expect a gradual deterioration to MVFR, with local IFR, later
this morning with increasing low level moisture ahead of an
approaching surface boundary/cold front. Additional showers and
thunderstorms are expected to develop along and ahead of this
boundary from mid to late afternoon. A general return to VFR is
expected after the passage of the front, with some dry advection
and mixing/gusty NW surface wind. Stratus is likely to then
develop overnight with low level moisture in place, and
diminishing wind.

Outlook...
Scattered showers and possible thunderstorms are expected
Wednesday, especially east of I-79, as the shortwave trough
deepens into a closed low across the NE CONUS. A return to VFR
is then expected (outside of any early morning vly fg) through 
Saturday as high pressure tracks east across the region.

&&

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

&&

$$

DISCUSSION...Frazier
AVIATION...WM