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536
FXUS61 KPBZ 301628 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1228 PM EDT Thu May 30 2024

.SYNOPSIS...
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Dry weather and moderating temperature are expected through
Saturday under the influence of high pressure. Late Saturday
through early next week will feature scattered showers and
thunderstorms. Temperatures climb back above normal early next
week with lower to mid 80s forecast.
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&&

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

- Mixing of drier air to the surface this afternoon may create
  slightly higher fire weather concerns.
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An area of stratocu east of Pittsburgh will continue to slowly
diminish through the morning as a weak shortwave trough crosses
the area and high pressure builds. Otherwise, the area will
remain dry and mostly clear today under the influence of high
pressure with afternoon fair weather cumulus. Dry advection
aloft and at the surface will promote abundant sunshine, but
residual cool advection will keep temperature around 5 degrees
below the daily average. Afternoon humidity values could fall
into the 30s and even upper 20s with peak mixing, but weak
surface wind plus saturated grounds should keep fire weather
concerns at bay.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Dry weather persists as temperature moderates.

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Friday and Saturday will feature the approach and passage of
brief shortwave ridging aloft that is wedged between the eastern
seaboard trough and an approaching central plains shortwave
trough. Moderating temperature is expected through Saturday when
afternoon highs will be slightly above the daily average. Plenty
of insolation will be seen Friday with the ridge axis overhead
while Saturday features increasing high clouds as warm/moist
advection ramps up ahead of the aforementioned shortwave trough.

&&

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

- Shower and thunderstorm chances increase late Saturday into early
  next week.
- Temperatures rebound back toward normal by Saturday.
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Ensemble guidance is coming closer into unison on the approach
and passage of a weak shortwave trough late Saturday night
through Sunday afternoon. Approach and passage of this feature
(and its likely weak surface cold front) will promote shower and
thunderstorm activity, though nocturnal arrival and excessive
cloud cover Sunday should keep lightning probabilities lower
(along with severe threats). There remains some uncertainty as
shortwave strength and forward movement likely is tied somewhat
to convective evolution over the lower Ohio River Valley
Saturday.

Quick passage of that trough should lend to broad ridge
development just south of the region Monday into Tuesday. This
synoptic pattern would favor above normal temperature with low
probability afternoon thunderstorms that will be predicated on
shortwave movement and convective evolution over the western
Great Lakes. Much variability in outcomes is seen within model
ensembles, which muddies any chance of entertaining severe
probabilities.

There is more consensus on the development of a notable upper
low pressure system mid to late week that would pose a far
greater probability for convective development and, to some
extent, severe chances.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
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Residual moisture in a heating boundary layer has yielded sct-
bkn cu in the 3-4kft layer for much of western PA this morning/
early afternoon. As mixing continues today, and dry air is
entrained into the boundary layer from above, there should be an
eventual erosion of clouds, with skc anticipated by early this
evening as high pressure becomes more assertive. Wind gusts
15-20 kt are common this afternoon amid the deep mixing, but
these will subside this evening amid decoupling and the building
high pressure. Despite a cool overnight, the drying boundary
layer is likely (90% confidence) to suppress fog formation at
most terminals, except perhaps FKL and vicinity of PIT (where
there is a 10-20% probability of vsby below 6SM late tonight).

Otherwise, there is a high-confidence VFR forecast next 24
hours.

.Outlook...
VFR is expected through Sat under high pressure. Potential for
flight restrictions returns late Sat and Sun with crossing low
pressure.
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&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
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PA...None.
OH...None.
WV...Frost Advisory from 2 AM to 8 AM EDT Friday for WVZ514.
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&&

$$

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