753
FXUS61 KPBZ 010631
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
231 AM EDT Sat Jun 1 2024

.SYNOPSIS...
Rain will return to the area late Saturday night into Sunday
with crossing low pressure. Above normal temperature and low
probability showers and thunderstorms are favored thereafter
until the next system arrives mid to late week.

&&

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

- Dry weather continues through this evening before rain moves
  in from the west.
- Temperatures will warm back above-normal on Saturday.
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Upper level ridging will shift east of the region through this
evening in response to the approach of a weakening shortwave
trough. The daytime hours will remain dry with increasing cloud
cover amid warm/moist advection aloft. Temperature is likely to
be near to slightly above the daily average.

Mostly light rain showers will arrive in the eastern Ohio zones
from the west after midnight (and likely closer to dawn Sunday)
in association with the weakening shortwave trough. Stable
overnight conditions and marginal shear should preclude
lightning development.

&&

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

- Showers and low probability thunder expected Sunday before
  tapering off during the evening.

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Gradual progression of the generally weakening shortwave trough
is expected Sunday, with the system generally exiting late
Sunday night. The associated precipitation areas will progress
across eastern Ohio during the morning hours then through
western Pennsylvania during the afternoon and evening. The
environment will feature minimal instability due to excessive
cloud cover (less than 500 J/kg SBCAPE focused mainly south of
I-70) and weak shear; this will limit storm strength (limited
severe threat) and rainfall rates/updraft organization (limited
flooding threat). The lack of stronger surface forcing and the
decaying dynamics of the shortwave will also create more of a
scattered coverage appearance, meaning some locations may see
little to no rain.

Dry weather should return by Sunday night with the loss of
daytime heating and exiting of the shortwave, with any lingering
showers confinded to upslope Laurel Highland zones. The lack of
notable dry advection behind the system could make fog a
potential overnight impact, depending on the degree/quickness of
cloud clearing.


&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Low probability showers and thunderstorms with above normal
  temperature likely to start the next work week.
- Increasing precipitation chances accompany a mid to late week
  low pressure system that will cause falling temperature.

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Subtle ridging stretching from the lower Tennessee River Valley
to the upper Ohio River Valley Monday is likely to promote dry
weather and slightly above average temperature. The probability
for showers and thunderstorms should be low and generally
confined to the higher terrain where better moisture and terrain
convergence may lead to an isolated afternoon storm. Little
change in the broad synoptic flow is expected for Tuesday, which
will promote above normal temperature and dry weather. That
said, there remains a scenario that convective evolution to the
west could push far enough east to increase precipitation
chances late Tuesday into Wednesday morning.

Ensemble means continue to favor the eastward progression of an
upper level trough into the western Great Lakes Wednesday. This
scenario would provide increasing large scale ascent/forcing to
promte more widespread hsowers and thunderstorms Wednesday into
Thursday. However, an alternate but plausible outcome is that
more staunch ridging will either delay trough arrival or deflect
its passage farther north; this would delay the next
precipitation chances while maintaining above normal
temperature.

Confidence is higher for general troughing to move over the
Great Lakes region by Friday that would promote periods of
showers and thunderstorms and downward trending temperature.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR will continue as high pressure moves east across the Upper
Ohio Valley region. Light and variable wind tonight will veer to
the SSE later this morning with speeds around 5 kt.

.Outlook...
Restrictions and showers/possible thunderstorms return Sunday
with a crossing trough of low pressure. Current ensemble
guidance indicate a 60-70% chance of MVFR on Sunday. MVFR to IFR
fog/stratus is possible Sunday night with low level moisture in
place. VFR returns later Monday and Tuesday under high pressure,
before a restriction and shower/thunderstorm potential returns
with a Wednesday cold front.

&&

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

&&

$$

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