309
FXUS61 KPBZ 051712
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
112 PM EDT Fri Jul 5 2024

.SYNOPSIS...
Shortwave passage may generate afternoon and evening convection
with a low probability threat for damaging wind and localized
flash flooding. Dry weather and rising temperature is expected
through Monday before the next disturbances approaches mid week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- A conditional threat exists for damaging wind and localized
  flash flooding this afternoon and evening.
- Uncertainty exists in convective and instability development
  to create hazard risk.

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A weak shortwave and surface trough are expected to lift
northeast through the Ohio River Valley through tonight, though
the trough axis may linger southeast of the region into
Saturday. Satellite and radar imagery show ongoing convection
entering SW Ohio where surface and elevated instability becomes
more limited. This highlights a growing conditional issue for
thunderstorms and severe weather today: both the 12z sounding
at KPIT and KILN show notable warm air aloft that is capping
available instability. Given area cloud cover and increasing
mid to high-level clouds moving NE off the decay convection,
there is greater uncertainty that storms will maintain and/or
develop as the shortwave regions this region as
heating/destabilization may not be realized until late this
evening when forcing better maximizes over the area.

That said, there remains a threat for hazardous weather (in the
form of damaging wind and localized) due to the elevated PWAT
values, increasing shear, potential for 1000-1500 SBCAPE, and
presence of some drier air aloft. It would remain conditional on
storm formation and instability maximization (which is likely
needed to overcome poor lapse rates), with current analysis
suggesting locations south of I-70 having the greatest
potential.

The shortwave will more notably pass between 00z-06z, which may
yield a greater uptick of storm development across western PA
but with a lower probabilistic severe environment. Passage of
the surface trough and upper wave will diminish precipitation
chances west to east and offer a slight reprieve from the warm,
muggy conditions.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- Dry and more seasonable weather returns on Saturday.

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Drier southwest flow and ridging at the surface will support dry
weather Saturday. Lingering morning stratus clouds are expected
to break up with a scattered to broken cumulus field developing
in the late morning to early afternoon; weak cool advection plus
the cloud cover should aid temperature returning to more
seasonal values. More notably for some, drier air will mix to
the surface and bring relief to the region from the multiple day
experience of humid conditions.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:

- High probability for dry weather and slightly above average
  temperature the rest of the weekend.
- Unsettled weather returns Tuesday through at least mid-week.

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Confidence remains high in dry weather continuing into the new
week as surface ridging remains over the Ohio Valley and upper
troughing persists over the Central Plains. Temperatures should
remain near-normal on Sunday, but increasing return flow and
warm advection on Monday ahead of the next low pressure system
will drive daily highs back above-normal. Ensembles indicate
more active weather Tuesday into Wednesday as low pressure
crosses and upper troughing sets up across the East. High
pressure will return for Thursday with most activity being a
slight chance or less but most likely dry.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
Scattered showers and thunderstorms will be possible late
afternoon / evening with a shortwave and ahead of a crossing
front. Have used a PROB30 for KMGW, but removed mention
elsewhere with low confidence in timing or location.

Cigs should lower into MVFR/IFR again overnight with lingering
moisture, eventually lifting Saturday morning as drier air moves
in behind the front.

.Outlook...
VFR conditions should persist through the weekend with high
pressure. The next chance for widespread restrictions will be
with our next system Tuesday.

&&

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

&&

$$

SYNOPSIS...Shallenberger
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...88