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408
FXUS61 KPBZ 311825
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
225 PM EDT Fri May 31 2024

.SYNOPSIS...
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Dry weather continues through the daytime on Saturday with
warming temperatures. Rain will return to the area Saturday
night and 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.
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&&

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

- Dry weather continues through Saturday.
- Temperatures will warm back above-normal on Saturday.
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Pleasant, sunny weather continues this afternoon as the upper
ridge axis crosses into the Ohio Valley and surface high
pressure remains centered over the region. Lingering dry,
northerly flow means you`ll be hard pressed to find a cloud over
the area through the afternoon.

The ridge axis and surface high will shift eastward overnight,
turning flow more southerly and increasing warm/moist advection.
Cirrus is expected to increase through the night which, with
increasing humidity and warm advection, may help reduce the
efficiency of overnight radiational cooling. Overnight lows are
expected to run from the mid-40s to low-50s across the area,
though pockets in the upper 30s are possible north of I-80.

Cloud cover will increase on Saturday as the trough crosses from
the Mississippi Valley into the Ohio by late day. Warm advection
will boost afternoon temperatures back to just above average,
yielding area highs in the upper 70s to lower 80s.
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&&

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

- Showers and low probability thunderstorms arrive late Saturday
  through Sunday.

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The shortwave trough will near the area late Saturday, crossing
on Sunday. Generally light rain showers are expected with this
system Saturday night through Sunday. Probability for thunder
will be low as even 75th percentile SBCAPE values don`t exceed
100 J/kg, though the highest chance for any rumbles will be
Sunday afternoon. Showers will continue through the day until
the wave exits, becoming more scattered/isolated in the
afternoon. Lingering showers should gradually wane through the
evening and overnight. Flooding/severe threats should remain
minimal due to weak instability and weak deep-layer shear.

Cloud cover and ongoing showers will limit diurnal heating,
keeping Sunday afternoon highs ten or so degrees cooler than
Saturday.
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&&

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

- Low probability showers and thunderstorms with above normal
  temperature likely to start the next work week.
- More widespread precipitation favored with mid to late week
  low pressure system.
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Ensembles generally favor gradual ridge building across the
Tennessee and Upper Ohio River Valleys Monday into Tuesday with
some shortwave movement to the north as troughing develops over
the northern Rockies. This should promote above normal
temperature and at least dry weather for Monday as subsidence
and weak flow keep diurnally driven convection very isolated.
The deviation for that forecast could come Tuesday if shortwave
movement is more robust/deeper to the north Tuesday, which would
increase convective potential during the day (favored ECMWF
route). Either scenario would still be somewhat dependent on
storm evolution well west of the region and its impact on the
larger scale flow.

The synoptic patter shows greater variation mid-week as not all
model solutions track the northern Rockies trough toward the
Great Lakes. Current model consensus, and this forecast package,
does trend toward the approaching/passing trough scenario which
would promote more widespread showers/thunderstorms during the
mid to late week period. If ridging proves to be more stout
ahead of the troughs approach, that could delay the uptick in
precipitation chances till next weekend while maintaining a
more dry and seasonable warm pattern. Nonetheless, the
variations remain too wide for any discussion of severe or
flooding threats at this time.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
High confidence forecast of VFR weather. High pressure centered
over the region will maintain light wind and limited cloud
coverage through the TAF period.

.Outlook...
The potential for flight restrictions returns early Sunday with
crossing low pressure. Latest guidance shows probabilities of
MVFR and IFR between 50%-70% and 20%-30% respectively on Sunday.

&&

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

&&

$$

SYNOPSIS...Rackley
NEAR TERM...Rackley
SHORT TERM...Rackley
LONG TERM...Rackley/Frazier
AVIATION...88/McMullen