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859
FXUS61 KPBZ 271310
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
910 AM EDT Mon May 27 2024

.SYNOPSIS...
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Spotty showers and a thunderstorm or two are possible again
during the afternoon as a cold front crosses the region. A few
cooler days are anticipated thru mid- week as low pressure aloft
becomes stronger in the eastern part of the country.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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KEY MESSAGES:

- An additional round of showers/storms will cross the region
  through dawn.
- Another round of potentially strong to severe thunderstorms
  this afternoon.
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The line of showers representing the last remnants of a decaying
MCS will exit the forecast area to the east by 14Z. Although
clouds are lingering behind the showers and may inhibit
destabilization to some degree, but breaks are likely to develop
once mixing gets going. The expected afternoon cold front is now
crossing into NW Ohio and will arrive this afternoon in an
environment with perhaps 1000-1500 J/kg of CAPE and around 30
knots of effective shear. Marginal risks of severe thunderstorms
(generally east of PA/OH border) and excessive rain (areawide)
remain in place.

Previous discussion...

A cold front is expected to approach the area between the 20Z
and 00Z mark with afternoon heating and forcing from the
boundary may lead to additional development. The SPC has left
the Marginal risk for severe and excessive rainfall for today.
Aided by daytime heating and slow passage of the cold front,
this round of strong to severe thunderstorms. That said, along
and ahead of the cold front, we`ll likely see additional
convection across eastern OH and western PA, but destabilization
remains in question owing to breaks of cloud coverage as
southwest flow aloft advects in moisture ahead of the front.
Large spreads in NBM low end vs. high end coverage lend lower
confidence to this aspect of the forecast. Mean CAPE is progged
around 1000 J/kg and effective shear near 30 knots, so some
strong to severe storms are possible with primary threats of
damaging wind and hail, but trends will need to be monitored.
Highs today will be cooler than those over the weekend with mid
70s most likely but dependent on the cloud cover.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Daily rain chances and below normal temperatures take over
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The convection developing with the passing cold front will
finally weaken and dissipate by 00Z to 03Z or advect off into
the northern area of CTP`s forecast area. That should saturate
the area as well for overnight tonight with a weak frontal
passage and light winds with some clearing possible. This will
set the stage for possible fog development.

The upper low will swing more shortwaves around its base and aid in
daily, diurnally driven scattered precipitation chances as well as
below normal temperatures. Late Tuesday into Wednesday morning may
feature the highest rain chances as a more potent shortwave and
surface trough cross the region with 24 hour totals ranging from a
trace to 0.75" at most.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:

- Cool temperatures continue through the end of the week
- Dry weather favored to take over by Thursday
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By Thursday, ensemble disagreement increases with the axis and
strength of the upper trough, but any flavor of solutions doesn`t
kick it out of the eastern CONUS until toward next weekend. Broad
surface high pressure should build on Thursday and turn the area
dry, but it`s possible that it`s slower to build and shower chances
continue into Thursday especially as a potent upper wave makes one
final pass through the area before upper ridging finally builds with
decent confidence among the long range ensembles. Lows may dip as
cool as the low to mid 40s come mid to late week as the cooler
airmass settles in with highs 5-8 degrees below average.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
With the overnight round of showers and storms exiting the area
to the east, expect brief improvement in conditions in its wake
before MVFR stratocu settle back in this morning. Ceilings will
then improve throughout the day as heating and mixing generally
raises cloud bases to around or above 5kft AGL by the afternoon.
A few showers and thunderstorms will be possible during
afternoon hours with associated local restrictions as well as
low-end potential for damaging straight line winds and large
hail. A weak front pushes through the area around 00Z, briefly
shifting winds to more westerly and ending rain chances across
the area. Mostly VFR then prevails overnight with the exception
of MVFR stratocu persisting north of I-80.

.Outlook...
Periodic restrictions and rain chances continue through mid-
week as a series of disturbances move through the region within
broad ern-CONUS low pressure aloft.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...CL/Shallenberger
SHORT TERM...MLB/Shallenberger
LONG TERM...MLB
AVIATION...Cermak/Rackley