715
FXUS61 KPBZ 050203
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1003 PM EDT Thu Jul 4 2024

.SYNOPSIS...
A series of disturbances will create periods of scattered
thunderstorms through Friday, offering low probabilities for
localized flash flooding and gusty wind. Dry weather with
seasonable temperature will return Saturday into Sunday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
KEY MESSAGES:

- Scattered showers and thunderstorms early this evening will
  become more numerous
- Locally heavy rainfall possible where training occurs

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One shortwave/vorticity maximum continues to track across
western PA, with a remnant MCV east of PIT. This will exit the
region this evening. Another shortwave/vorticity maximum was
crossing western Ohio, with additional showers and thunderstorms
ahead of it. The next wave should cross the area this
evening/overnight, with showers and thunderstorms becoming more
numerous.

The 00Z PIT sounding shows precipitable water at 2.13 inches,
with ML CAPE near 1000 j/kg. Mid level lapse rates are weak with
warm air aloft. This is likely the limiting factor on stronger
storms this evening. The latest mesoanalysis shows an overall
decrease in CAPE values over the last three hours. Shear has
increased to near 40kt, though with the weak mid level lapse
rates most of the storms have not been able to strengthen. The
main concern remains localized flooding where training of
thunderstorms occurs.

The severe weather potential should gradually wane overnight,
with the localized flood potential likely continuing until
shortly after midnight. Showers and thunderstorms should taper
off from west to east later tonight as the shortwave exits.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- More widespread coverage is expected Friday, with damaging
  wind and flash flood threats remaining possible.
- Dry and more seasonable weather returns on Saturday.

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A more organized shortwave and surface low pressure crossing
the Great Lakes will lift the stationary boundary northward as a
warm front and push a late-day cold front through the region.
Breaks in cloud coverage and weak cooling aloft should help
destabilize the otherwise unchanged environment (modest CAPE,
moderate shear, weak lapse rates, high PWAT values). The
expectation is for greater shower and thunderstorm coverage
during the afternoon and evening Friday ahead of each boundary,
with damaging wind and localized flash flooding threats
possible. Improved forcing and instability should be negated by
stronger storm flow to leave the overall flash flood threat
similar to that seen today.

Passage of the surface cold front and upper shortwave will
diminish storm chances Friday night, with dry and seasonable
weather returning on Saturday.

&&

.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 through the
weekend 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 mid-week as low
pressure crosses and upper troughing sets up across the East.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Hi-Res guidance has been consistent that cigs will drop to
MVFR/IFR into early tomorrow morning as a new mesoscale feature
advances into eastern Ohio and western PA and stirs a new round
of convection. Isolated showers/storms that advance over
terminals may experience a brief period of IFR/LIFR vis.
However, with convection being so disorganized, confidence is
low on which terminals will be impacted in advance; amendments
will likely be necessary while monitoring the radar.

IFR to MVFR conditions may linger through 16Z under a lingering warm,
moist air mass.

Additional rounds of showers and thunderstorms (with occasional
restrictions) are expected through early Sat as a cold front
slowly crosses. Any storms in the vicinity of terminals could
drop restrictions to MVFR/IFR briefly, especially vis with heavy
downpours.

.Outlook...
VFR should return Sun amid high pressure.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...WM
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Hefferan