839
FXUS61 KPBZ 092356
AFDPBZ

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

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH FRIDAY/...
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.
-------------------------------------------------------------------

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.

&&

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

- Showers chances continue into Friday.
- Below average temperatures are expected with northerly flow.
- Thunderstorms chances return Saturday afternoon.

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

Precipitation chances will remain across the region on Friday
due the slow progression of the trough over the Mid-Atlantic,
slowed down by ridging over the Mississippi River Valley.
Probability of higher rainfall amounts (0.25 inches to 0.45
inches) will generally be focused east and southeast of
Pittsburgh due to orographic lift. Elsewhere, showers will only
amount to less than quarter of an inch.

Ridging over eastern Ohio Friday night into early Saturday is
expected to decrease precipitation. Temperatures will remain
cooler than average under northerly flow.

By late morning Saturday, a new fast moving shortwave dives
southeast from the Great Lakes and returns showers and isolated
thunderstorms to the region. A few storms could be considered
strong given high shear and MUCAPE values between 500J/kg to
1000J/kg.

&&

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

- Cooler temperatures arrive by late week with highs in the 60s
  this weekend.
- Rain and thunderstorms are expected to return
  Tuesday/Wednesday.
- Severe storm potential remains low.
-------------------------------------------------------------------

A few light showers may remain along the ridge line early Sunday
as a trough exits east. Otherwise, dry and quiet weather return
for a majority of the day with building high pressure.
Temperatures will be near or slightly below average, depending
on have fast the clouds clear from the west.

Warmer than average temperatures Monday and will continue into
Wednesday as a slow moving low ejects out of the Great Plains
and reinforces southwest flow. As high pressure breaks down off
the Mid-Atlantic, showers and thunderstorms chances increase
Tuesday and Wednesday. Long range models at the moment project a
low probability of severe storms given weak shear and
instability.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Thunderstorms south of the PA/WV border will continue to sink
to the south and east, exiting the forecast area by 02Z. Several
terminals have already deteriorated to IFR, and expect most
others to follow during the evening as low pressure passes to
the south, with abundant showers and low-level moisture. Shower
coverage will decrease after midnight, but fog/mist will linger
along with the IFR ceilings.

Restrictions will linger through Friday morning before some
improvement during the afternoon as a shortwave trough axis
passes, slowly ending the scattered shower threat and lifting
ceilings. Some terminals may achieve VFR by 00Z.

.Outlook...
Periodic restrictions will likely continue into Saturday 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...Hefferan
LONG TERM...Hefferan
AVIATION...CL