653
FXUS61 KPBZ 052350
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
750 PM 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 /UNTIL 6 AM THURSDAY MORNING/...
KEY MESSAGES:

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

Mesoscale 6PM Update: Current conditions show a break in the
convection as the first wave passed through and the last of the
showers are exiting into State College`s forecast area.
Meanwhile, another trough is beginning to advect into central OH
as convection continues to develop into central and northern OH
as it begins to cross into the PBZ forecast area. However,
mesoscale conditions hint at a bit of inhibition in far
southeast OH and may be the culprit that is causing convection
dissipate as it crosses into the southeast OH counties of the
Pittsburgh forecast area. This, despite the lingering SFC based
CAPE of 1500 to 2000 J/Kg along the OH/PA border. With minimal
CAPE, the severe threat seems more uncertain, but the flood
threat will remain as even the smaller cells that passed through
Indiana County PA still caused some basins to respond quickly to
the efficient rainfall rates. Will continue to monitor for the
flood threat across the area.

Previous discussion...Another shortwave trough is expected to
traverse the area through this evening ahead of a cold front.
The mentioned shortwave will cross the region late this
afternoon. NBM is showing higher probs for rainfall this
afternoon over the ridges but the warm rain process in effect
throughout today will make just about any area a concern for
heavy rainfall. Its also worth mentioning that PWATs seem to be
elevated for the amount of moisture in place. The 12Z morning
PIT sounding shows 1.66 PWAT and a freezing level at 12 KFT with
a good bit of the SFC to 500MB being saturated. 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. To that fact, the
tornado 2% has been removed by SPC and only a wind and flood
threat remain. For the most part heading into the evening, there
still appears to be some instability as sfc based CAPE values
remain in between 1000 and 2000 J/Kg across the area with at
least some 30 knots of bulk shear. The severe threat remain
minimal but still possible.


A cold front will cross our area late tonight with the potential
for additional convection through the overnight. This should
keep fog at a minimum but also temperatures will be warm
overnight with the persistent cloud cover. Lows will remain in
the middle 60s for low tonight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
KEY MESSAGES:

- Risk for scattered showers/storms continues on Thursday with
  the passage of a deep trough.
- Continued activity on Friday with cooler temperatures.

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

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. Thursday
afternoon seems to be a period to watch for as well with MU CAPE
values between 500 and 700 J/Kg with nearing 50 knots of shear.
SPC has a general thunder this day but there certainly could be
a strong storm with this passing post frontal trough.

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 and scattered showers.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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 Friday night into
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.

The pattern will change by Tuesday next week as the upper low
finally gets shunted to the east with riding finally moving back
into the region. This will mean dry weather possibly returning
for Tuesday and Wednesday next week as rain chances remain below
30%.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
The TAF period begins with VFR conditions and light rain
showers, excluding upslope IFR low ceilings at DUJ. However,
this will soon change, as a trough and an associated cold front
bring convection into the region during the late evening and
into the overnight hours. Have used two-hour TEMPO groups to try
to time the most likely arrival of thunderstorms at each
terminal. Confidence in thunder occurrence for terminals east of
PIT is lower than west, as the loss of diurnal heating may
reduce precipitation to showers; nevertheless, ceilings are
likely to drop through MVFR to IFR as the trough and front
cross. Other storm impacts could be variable wind gusts in the
30 to 40 knot range, as well as brief downpours creating
IFR/LIFR visibility for a short time.

Low ceilings will linger through sunrise at most terminals with
some patchy 4-6 mile mist, before improvement to VFR in daytime
mixing behind the front. Steep low-level lapse rates will likely
promote wind gusts in the 20 to 25 knot range by midday
areawide, with some modest instability creating isolated showers
as well.

.Outlook...
Periodic restrictions and scattered showers are expected
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...Shallenberger
NEAR TERM...Shallenberger
SHORT TERM...22/Shallenberger
LONG TERM...22/Shallenberger
AVIATION...CL