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827
FXUS61 KPBZ 091625
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1225 PM EDT Thu May 9 2024

.SYNOPSIS...
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Strong to severe thunderstorms have the potential to develop
near or south of I-70 this afternoon. Cooler conditions are
anticipated over the weekend with a shift in the synoptic
pattern from the northwest.
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&&

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

- There will be a window of opportunity for strong to severe
  storms to develop south of Pittsburgh this afternoon/evening.
- Damaging wind and hail could occur in a few storms.
- Urban flooding may also occur in areas of training storms.
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The center of low pressure system is currently located in
central Indiana at the moment. Based on ground observations
across the region, the warm front is situated along I-70. Low-
level water vapor depicts pockets of drier air advancing into
south Ohio, which is helping break the cloud deck, raise
temperatures, and increase the potential for destabilization.

As the center of the low ventures east into the Ohio River
Valley, wind shear in the southern sector of the low will
increase rom the west/southwest. Therefore, with pockets of
instability and high vertical wind shear, the potential for
organized convection increases south of Pittsburgh late this
afternoon and into the early evening. The combination of fast
tracking icy cores within storms raises the concern for damaging
winds near or south of I-70.

With convection racing across the moisture boundary from west to
east, there is also a threat for isolated flooding south of
Pittsburgh. Urban areas will be vulnerable to flooding with low
flash flood guidance. Probability of widespread rainfall totals
for counties south of I-70 range from 35% to 60% (with higher
values located near Uniontown,PA and Morgantown,WV). However,
probabilities will likely increase for a small communicates
within this large scale area if rainfall rates range from 0.5 to
0.7 inches per hour.

The probability of severe storms decreases with the loss
diurnal heating and ongoing convection tainting the environment after
8pm. However, there could be a few storms that could continue to
produce lightning.

With clouds, convection throughout the day, and cool northeast
flow, temperatures will likely trend cooler than average for
areas north of I-70; near average for areas south with in the
warm sector.
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&&

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

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

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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 /16Z THURSDAY THROUGH MONDAY/...
MVFR cig restrictions with rain will return from the south
after today as a sfc low passes south of the region. Any TSRA later
in the afternoon should be limited to ports south of KPIT.

It becomes increasingly likely that cigs will lower to IFR/LIFR
from the south after 00Z 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.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...Shallenberger
LONG TERM...Shallenberger
AVIATION...88