259
FXUS61 KPBZ 050055 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
855 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 /01Z FRIDAY THROUGH TUESDAY/...
Ceilings have generally lifted to VFR/MVFR to start the TAF
period, with additional improvement expected through the
remainder of the afternoon. Scattered showers and thunderstorms
are expected to move across the area through late afternoon and
early evening, and then possibly a second round overnight. Still
a fair amount of uncertainty regarding coverage, prompting VC in
TAFs except in a few scenarios where there is greater confidence
in at least enough coverage to expect impact to a terminal (in
which cases TEMPOs were substituted). Winds remain light and
variable (generally out of the southwest) outside of
thunderstorms. Gusty winds and restrictions can be expected in
and around storms. There is growing confidence in the return of
low cigs Friday morning, especially in areas that see heavy rain
today/tonight.

.Outlook...
Additional rounds of showers and thunderstorms (with occasional
restrictions) are expected episodically through early Sat as a
cold front slowly crosses. 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...Cermak/Kramar/Shallenberger