773
FXUS61 KPBZ 020457
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1257 AM EDT Sun Jun 2 2024

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

&&

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

- Dry weather continues through this evening before rain moves
  in from the west overnight tonight.
- Lows around 10-15 degrees warmer than Friday night.
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The forecast remains on track this evening as upper level cloud
coverage increases from the west with moisture advection ahead
of a weakening shortwave. With plenty of dry air below 400 mb
the 00z PIT sounding, precip may struggle a bit at onset until
saturation can occur...

Mostly light showers will arrive late tonight and Sunday morning
ahead of the shortwave. Latest model trends have continued the
slower trend of showers putting onset of rain in the eastern
Ohio zones most likely after midnight and into the Pittsburgh
metro near sunrise Sunday. Stable overnight conditions and
marginal shear should preclude lightning development.

Warm advection, increasing moisture, and overcast conditions
will keep area temperatures 10-15 degrees warmer than last
night.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
KEY MESSAGES:

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

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The weakening shortwave trough will cross the region on Sunday,
eventually pushing an associated surface cold front through by
Sunday evening. Showers will progress across eastern Ohio
during the early morning hours, then into and across western PA
during the morning and afternoon hours. Excessive cloud cover
should limit instability. Coincident with weak shear, this will
limit thunder potential and minimize storm strength/severe
potential. The lack of strong surface forcing and diminished
upper support will also lead to more scattered coverage. Though
the occasional brief heavy downpour remains possible, these
factors will keep the flooding threat minimal, and 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/weak front. Any
lingering overnight showers will be confined 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.

Rain and overcast conditions should keep Sunday temperatures on
the cool side, with most of the area in the upper 60s/lower 70s
during the afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:

- Low probability/low coverage showers and thunderstorms with
  above normal temperature Monday and Tuesday.
- 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. However, it is becoming more likely that rain chances
with the next system will begin as early as Tuesday night into
Wednesday morning.

Weather for the remainder of the week will likely be under the
influence of a large, elongated stacked low pressure system
meandering across Manitoba and Ontario into the Great Lakes.
Ensemble means favor increasing large scale ascent/forcing for
our region on Wednesday, promoting more widespread showers and
thunderstorms Wednesday into Thursday, likely most focused
along/ahead of an associated cold front crossing on Thursday.

Lingering low pressure across the Great Lakes/Ontario/Quebec
into the weekend will likely promote periodic
showers and thunderstorms with a downward trend in temperature.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
The approach and passage of a weak upper level shortwave trough
will foster areas of light rain this morning that become more
scattered showers during the afternoon before it exits this
evening. Probability for lightning never exceeds 20 percent, and
thus no lightning is mentioned in TAFs.

VFR conditions are favoring at all terminals through 12z (8am),
with only 30 percent probability of MVFR conditions at KZZV.
After 12z, uncertainty increases in timing of potential
restrictions; ensemble probability never rises above 50 percent
for MVFR cigs at KPIT until the end of the TAF period while
deterministic guidance suggests an 16z onset and persistence
thereafter. The most likely outcome is periods of VFR mixed with
MVFR throughout the afternoon and evening hours.

Depending on boundary layer moisture and clearing of residual
stratocu, fog and/or low stratus may develop Monday morning.
However, variability on potential outcomes for that period
remains high.

.Outlook...
Upper riding and surface high pressure will support a return to
VFR conditions by Monday afternoon with a dissipating field of
diurnal cu.

The next low pressure system is favored to arrive Wednesday
afternoon and evening and promote fairly widespread showers and
thunderstorms.

&&

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

&&

$$

SYNOPSIS...Rackley/Frazier
NEAR TERM...Rackley/MLB
SHORT TERM...Rackley
LONG TERM...Rackley/Frazier
AVIATION...Frazier