825
FXUS61 KPBZ 090749
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
349 AM EDT Thu May 9 2024

.SYNOPSIS...
Showers and thunderstorms will return, mainly south of
Pittsburgh, as a frontal boundary turns around and approaches as
a warm front through dawn. Thereafter, unsettled weather
continues, with periodic showers and storms Thursday through
Saturday.

&&

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

- A frontal boundary will serve as a point of initiation for
  showers and thunderstorms through the day.
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A stationary boundary will be in place across southern OH and
northern WV through the morning hours and through dawn. Showers
and thunderstorms will develop along the boundary and slowly
lift east and north through the early morning hours. This line
is expected to dissipate with only showers expected through
dawn. Thus, expect warmer temperatures and ample cloud cover
through dawn.

Heading into the coming day. A surface low pressure system will
begin to develop to the south along the Mid Appalachian Range
and slowly slide east. As this feature slides east, further
deepening of the low will assist increase south flow and thus
more moisture advection adding to an overrunning setup into
eastern OH and northern WV and eventually into southwest PA.
This will include a flood threat this afternoon and evening
along with a marginal severe threat as a shortwave crosses the
Upper OH Valley during the evening. Based on instability, the
threat still appears to be minimal, but with at least 500 to 700
J/Kg for the 20Z to 00Z timeframe and roughly 50 knots of shear
or more, there will be a chance for strong to severe storms. The
flood threat will depend on where the heaviest axis of rainfall
sets up but with the NBM DESI probs showing 30% to 50% prob of
greater than an inch for the northern WV and southern SW PA
counties, it does seem to once again become a dual threat
heading through tonight.

&&

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

- Showers/storms continue into Friday and Saturday.
- Ensembles suggest a wet pattern into the weekend.

-------------------------------------------------------------------

The low pushing east will be slowed by surface high pressure
over the east coast. This will allow enough forcing in the area
to keep showers and possibly a few thunderstorms in the area for
Friday. The low will eventually exit by Friday evening but a few
showers are expected to remain given a return to northwest flow
owing to a slight upslope component and lingering gradient.

By Friday night into Saturday, another fast moving shortwave
dives southeast in northwest flow bringing another round of
showers to the area. Overall, a rather damp weekend is on tap.

&&

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

- Cooler temperatures arrive by late week with highs in the 60s
  this weekend.
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The trough that brought some showers and a few thunderstorms
will continue into Saturday night as the main axis of the
trough begins to exit the area by Sunday morning. However, given
the return to northwest flow behind the trough and a lingering
weak shortwave trough behind the departed front will keep a
chance of showers and possibly a thunderstorm through the day on
Sunday. By Monday, the models suggest a brief break in the
pattern suggesting a shortwave ridge passing through before the
next disturbance. This will be evident as the warm front sets up
across the northern portion of the forecast area by Monday
afternoon.

The low further develops as it shifts east and the main trough
axis crosses southern OH keeping unsettled weather across the
area through the middle of next week.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
MVFR cig restrictions with rain will return from the south
after 12Z as a low pressure system tracks through the region.
Probability for thunder is expected to increase after 16Z with
daytime heating. A few storms south of PIT may be severe in the
afternoon/evening. Rain should generally taper off overnight.

It becomes increasingly likely that cigs will lower to IFR/LIFR
from the south after 00Z Friday with lingering moisture and
cooler conditions behind a cold front.

.Outlook...
Restrictions will likely continue through Friday afternoon with
lingering low-level moisture and cold advection from the
northeast.

&&

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

&&

$$

SYNOPSIS...CL
NEAR TERM...Shallenberger
SHORT TERM...Shallenberger
LONG TERM...Shallenberger
AVIATION...Rackley