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092
FXUS61 KPBZ 230454 AAC
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1254 AM EDT Thu May 23 2024

.SYNOPSIS...
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Showers and storms are possible today mainly south of
Pittsburgh. Seasonably warm highs today. Periodic thunderstorm
chances are expected through the holiday weekend as a series of
upper level disturbances cross the region.
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&&

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

-Showers and storms are possible today, mainly south of PIT as a
 cool front stalls just south of the region.
-Cooler temperatures today, but still seasonable.
 _____________________________________________________________

For the overnight period...have updated the PoPs to better
reflect current conditions and the latest hires guidance.
Activity is having a difficult time developing ahead of the slow
moving cool front due to a lack of upper level support, a
stabilizing atmosphere, and warmer air aloft that is creating a
cap that can be seen on the 00Z PIT sounding. Will still keep
in the risk for showers/storms overnight, but its looking more
isolated to scattered. Temperatures will remain mild.

A cool front will drift south and east of the forecast area this
morning, stalling over the northern reaches of the Mid-Atlantic
region. This will allow for a break from convection for a
portion of the morning hours. The question for the afternoon is
the path of a shortwave trough which will move eastward in the
vicinity of the quasi-stationary front this afternoon. Seeing
some differences in model solution with the track of the wave.
This is due to the influence of a second, albeit weaker,
shortwave that will move across northern Ohio/PA this afternoon.
Some of the operational models want to almost phase the two
waves allowing for rainfall to spread further north. While,
other models want to keep them separate and focus on the
northern wave pushing the southern wave further south. Latest
blended guidance is trying to find a happy medium, but is
focusing the higher PoPs mainly south of I-70 this afternoon.
The latest CAM models are leaning toward a more southern track
of the wave, keeping much of the area dry. With so much
uncertainty for this afternoon will lean heavily on the blended
guidance.

The resting place of the front and track of the shortwave will
also play a role in how much convection can re-fire this
afternoon. Obviously a further south placement would keep the
higher levels of instability/buoyancy further south, limiting
storm development.

Cloud cover will also depend upon how far south things settle,
as drier air will be spreading southward behind the front. There
is a good chance that the I-80 corridor could see plenty of
sunshine today.

Temperatures will cool a few degrees, but still remain
seasonable.
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&&

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


- High pressure and brief ridging should keep the area dry
  Friday.
-A crossing shortwave will return the risk for showers and
 storms Saturday.
 _____________________________________________________________

Confidence is increasing that dry weather will develop Thursday
night into Friday as shortwave ridging crosses the region with
high pressure at the surface. Minimal airmass change with
slightly higher heights should promote above normal temperature
again.

Ensembles are leaning toward a wave crossing the region
Saturday producing showers and thunderstorms; timing varies,
but potential exists for convection to exit east of the area
before evening activities. That variability leads to an
inconclusiveness on severe potential but note that analogs for
the pattern and machine-learning analysis suggests at least a
low probability for hazardous weather that day.
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&&

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

- Variability remains high on long term forecast and may be
  predicated on prior day`s convective outcomes.
- Overall, periodic showers and thunderstorms with slightly
  above normal temperature is favored through the holiday
  weekend and into next week.
  ____________________________________________________________

A more well-organized low pressure system is becoming the
favored pattern development to end the holiday weekend as it
lifts through the Great Lakes. Higher probabilities for showers
and thunderstorms are expected during this time frame but it is
unlikely to be "all day" rain type of events. Early analogs for
this pattern also suggest at least a low probability for
hazardous weather, but much variation in that potential remains.

Long range suggests a shift to a cooler, dry pattern by the
middle of next week as upper troughing develops over the Great
Lakes. Expect temperature to fall below the seasonal average,
with Tuesday potentially being the transition day from shower
activity to dry weather.
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&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
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A general VFR forecast for the period. The best chance for a
shower or storm to hit a port would likely be prior to dawn.
Have covered this early threat of convection with a tempo group
with a brief reduction in vis/cigs possible. This is done with
low confidence as probabilities of a storm hitting a port is
minimal.

Additional showers and thunderstorms may develop this
afternoon primarily south of PIT which could return associated
chances for restrictions later in the afternoon.

.Outlook...
Periodic thunderstorm chances and restrictions are likely
through the weekend as an active weather pattern continues.
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&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22/Frazier
LONG TERM...Frazier
AVIATION...22