061
FXUS61 KPBZ 050456 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1256 AM EDT Wed Jun 5 2024

.SYNOPSIS...
Widespread showers and storms return today. Unsettled weather
will remain into the weekend. Cooler temperatures return Friday
and hold through the weekend.

&&

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

- Shower and storm chances increase today with the passage of an
  upper level wave.
- Another warm day.
--------------------------------------------------------------

Some minor timing differences in the PoPs late tonight. A weak
shortwave trough will cross the region before dawn, increasing
deep moisture and the risk for showers. Rainfall should be light
as much of the wave`s energy will be used to break down the
ridge. Temperatures overnight will remain mild.

A series of shortwave troughs will cross the region today. The
first, which will move through this morning, will flatten and
push the eastern ridge over eastern PA. This wave will also
thicken and lower cloud cover. Showers will overspread the
region from the southwest. Seeing some differences in coverage
of the activity this morning. Rainfall should be light. Latest
NBM probs for measurable rainfall (>0.01 inches) generally range
from 50 to 70%. Probs for >0.10 inches fall off to 20 to 30%
this morning.

A more significant shortwave will cross the region this
afternoon with its focus on locations south and east of
Pittsburgh. NBM is showing higher probs for rainfall this
afternoon over the ridges. Latest CAM models are also
broadcasting the more likely place for stronger afternoon
convection and heavier rain east of PIT. Instability will be
descent this afternoon, but strong wind shear will be lacking.
What shear is available will ride up along the higher elevations
ahead of the shortwave. Cloud cover and warm air aloft will be
limiting factors today as well.

&&

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

- Cold front crosses late tonight keeping in the threat for
  showers and storms.
- Risk for scattered showers/storms continues on Thursday with
  the passage of a deep trough.
- More activity on Friday with cooler temperatures.

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

A cold front will cross our area late tonight. Showers and
thunderstorms are expected to develop ahead of this front in the
warm sector. Modest deep-layer shear to around 30-40 kts during
the evening may support isolated severe storms, with damaging
wind as the primary hazard. An isolated weak tornado cannot be
ruled out, though that threat will mainly remain mainly south of
PIT. However, early rounds of rain and overcast conditions,
along with waning instability after dark, may act to hamper this
threat. The latest Day 2 Outlook from SPC includes a Marginal
Risk for much of the forecast area, with a 5% wind threat and 2%
tornado threat.

Lingering showers/storms will end Thursday morning as the cold
front exits to the east. A deep shortwave trough is expected to
swing through Thursday afternoon. This will likely return
showers and storms Thursday afternoon/evening.

Just above-average highs expected Thursday.

Highly anomalous upper level low will move across the Great
Lakes on Friday. Waves of energy will swing around the low as
will much cooler air. This will keep our weather unsettled on
Friday. Temperatures should be noticeably cooler Friday with
plenty of clouds, scattered showers and 850T of +5 to +9. Will
go with NBM 10th pct for highs Friday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
KEY MESSAGES:


- Periodic showers with cooler conditions are expected through
  the weekend with a slowly crossing upper-level low.

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

The upper-low will dig into New England by Saturday. This will
keep cooler and showery conditions in the forecast as we head
into the weekend and into early next week. While there is low
confidence on pinpointing the best timing of these showers each
day, ensembles do agree on the general showery pattern with
upper troughing persisting through the weekend and possibly into
early next week.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR is expected through early morning as a shortwave ridge moves
east of the region. Scattered showers are expected to move
across the region this morning, with increasing moisture and
ascent ahead of an approaching shortwave trough and surface cold
front. Local restrictions are possible in these showers, though
uncertainty in location and timing of the showers precludes more
than a VCSH inclusion in the TAFs.

A mid level trough, ahead of the main approaching shortwave, is
expected to lift across the Upper Ohio Valley region this
afternoon. This should be the focus for showers, and
thunderstorms, as destabilization occurs. ML CAPE is expected to
be around 1000 j/kg as the initial trough crosses. Inoculated a
more focused Prob30 line in the tafs for this feature.

The main shortwave trough, and its associated surface cold
front, is expected to cross the region late this afternoon and
tonight. Additional showers and thunderstorms are expected, with
higher probability of occurrence than the mid afternoon
activity. Included a Tempo line for thunderstorms in the tafs to
focus on this feature as it crosses.

.Outlook...
Periodic restrictions and scattered showers are expected
Thursday through Sunday as a slow moving upper low persists
across the Great Lakes region.

&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...Rackley/22
LONG TERM...Rackley/22
AVIATION...WM