538
FXUS61 KPBZ 011735
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
135 PM EDT Sat Jun 1 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 /THROUGH TONIGHT/...
KEY MESSAGES:

- Dry weather continues through this evening before rain moves
  in from the west late tonight.
- Warmer temperatures in the upper 70s and lower 80s are
  expected this afternoon.
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Despite another cool start to the morning, today will end up
being a beautiful first day of Meteorological Spring. The upper
ridge and surface high pressure will continue to slowly shift
east today, keeping dry weather in the forecast at least through
the evening hours. Despite broken cirrus on satellite, plentiful
sunshine is expected into the afternoon before increasing cloud
cover later this afternoon and tonight. Despite increasing
cloud cover, warm advection will boost afternoon temperatures to
just above normal, pushing highs into the upper 70s to lower
80s.

Mostly light showers will arrive late tonight and Sunday morning
ahead of the weakening shortwave. Recent model trends have
slowed onset of showers slightly, putting onset of rain in the
eastern Ohio zones 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 /SUNDAY THROUGH SUNDAY NIGHT/...
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 THROUGH FRIDAY/...
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 /18Z SATURDAY THROUGH THURSDAY/...
VFR will continue as into the evening as high pressure slowly
edges east of our region. Mid and upper clouds will dominate
through then evening hours, slowly lowering and thickening with
time.

An approaching, weakening shortwave trough will push some light
rain showers into eastern Ohio after 06Z, with coverage slowly
expanding across the Upper Ohio Valley through the morning. NBM
probabilities of MVFR ceilings are 60-80% areawide after 12Z,
and have included that thinking in the TAFs. Best chance of
dropping to IFR is at ZZV according to the same blend, with
lesser chance to the east. This seems reasonable, as daytime
mixing may prevent ceilings that low later in the morning.

Wind will remain light through the TAF period, with a slow veer
from southeast to southwest with time.


.Outlook...
Restrictions and showers/possible thunderstorms continue into
Sunday evening as the shortwave crosses. MVFR to IFR fog or
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...Rackley/Frazier
NEAR TERM...Rackley
SHORT TERM...Rackley
LONG TERM...Rackley/Frazier
AVIATION...CL