-- Discussion containing changed information from previous version are highlighted. --
766
FXUS61 KPBZ 301138
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
738 AM EDT Thu May 30 2024

.SYNOPSIS...
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Dry weather and moderating temperature is expected through
Saturday under the influence of high pressure. Late Saturday
through early next week will feature scattered shower 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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Weak shortwave movement on the backside of an exiting upper
level trough will continue to promote areas of stratocumulus
east of Pittsburgh this morning. This cloud cover should wane
with impinging high pressure, but its persistence will likely
mitigate widespread morning fog development.

The rest of the day is expected to be dry under the influence of
high pressure. 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 /12Z THURSDAY THROUGH MONDAY/...
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High confidence forecast of 90%. IFR at DUJ and MVFR at LBE/MGW
will lift no later than 14Z, most likely by 13Z. Afterward, VFR
with a clear sky and wind less than 10kts.

.Outlook...
VFR is expected through Saturday under high pressure.
Restriction potential returns late Saturday and Sunday with
crossing low pressure.
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&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...McMullen/WM