589
FXUS61 KPBZ 102355
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
755 PM EDT Wed Jul 10 2024

.SYNOPSIS...
Mostly dry conditions with cooling temperatures expected through
Thursday under building high pressure. Temperatures then
rebound Friday into the weekend on Friday and precipitation
chances return for the beginning of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
KEY MESSAGES:

- Some lingering light drizzle/showers through the overnight.
- Wind gusts to 25-35 mph continue through sunset.
- Cooler air settles in with lows dropping to just a couple
  degrees above normal.
-------------------------------------------------------------------

Evening update...made adjustments to overnight PoPs as
scattered/isolated light rain showers are developing in the cold
air advection. Cloud cover was also adjusted as a large area of
stratocu will cover and settle in over the region tonight. Temps
were warmed by a degree or two due to the cloud cover.

Previous discussion...

With mixing into a 30-40 kt 850 mb jet, gusts to 30-35 mph will
continue through sunset, but should largely remain below
advisory criteria save for a sporadic gust here and there.
Still, it will be uncharacteristically windy for this time of
the year. Otherwise, with the cloud coverage overhead and
despite the cold advection at the surface, lows will hold a
couple degrees above normal.

&&

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

- Lingering moisture with cooler temperatures on Thursday.
- Dry Friday as temperatures rebound back to above normal.
-------------------------------------------------------------------

Upper troughing will linger across the lower Great Lakes, but good
ensemble agreement supports it weakening and  as ridging off to
our east noses in and heights rise slightly into the day on
Friday. As the remnants of Beryl depart, high pressure builds in
its wake. Residual northwest flow through the first half of
Thursday will support a cold season looking pattern with lake
enhanced cloud coverage especially north of Pittsburgh as
moisture is still trapped under subsidence. Hi res ensemble
soundings show a very shallow, conditionally unstable layer,
that may support low probability light showers/drizzle north of
I-80 during the morning. Otherwise, the day will be dry with
highs dipping down to or just below climatological normals.

The high establishes just to our east on Friday and flow veers east
to southeast with much higher confidence in mostly clear skies given
little spread in ensemble cloud cover distribution. This, combined
with warm advection aloft, will rebound highs back above average to
the upper 80s/low 90s. Dew points should remain low enough with
diurnal mixing to preclude heat headlines.

&&

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

- High confidence in well above normal temperature leading to
  increased heat risks through the middle of next week.
- Early indications suggests increased precipitation chances
  during the period with non-zero severe weather potential.
-------------------------------------------------------------------

Flow becomes a bit more zonal on Saturday as ridging across the
western CONUS amplifies. Locally, we`ll remain under high
pressure through most of the day on Sunday and hot and humid
conditions return as ensemble probability for highs >90F
increases to 60-80% both days this weekend.

Ensembles favor a continuation of those hot and humid
conditions to persist through next week, and clusters are in
overall good agreement on the evolving pattern, but not
necessarily with the finer scale details. Models suggest
several rounds of shortwaves will occur through next week that
lower heights over the region and introduce increased
precipitation chances. Details are too noisy to discern, but a
prolonged northwest flow pattern is typically a signal of a more
active period of weather in our region, potentially emblematic
of a series of MCSs traversing the Great Lakes with potential
impacts/timing (and alterations to temperature) being influenced
by previous days outcomes. This pattern recognition is noted in
various AI weather models, meaning that there is a non-zero
chance for hazardous weather (with a damaging wind threat being
the highest probability hazard). Have continued the mention in
the HWO along with potential heat to aid decision makers to
monitor the latest trends.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Cigs are expected to fall to MVFR/IFR overnight with decreasing
winds. At all ports, MVFR is favored with 80% to 100%
confidence, except for MGW, at a 65% chance overnight. IFR is
most likely at BVI, FKL, and DUJ with just a 50% to 60%
probability, decreasing slightly after 05Z.

The mixed layer will gradually stabilize overnight as cold
advection forces saturation and decreases low-level lapse rates
below 700mb. This will result in relaxing wind gusts through
Thursday morning. While ZZV may be the first port where winds
lighten, there is still a 60% chance of gusts greater than 18kts
through 12Z-16Z tomorrow.

Guidance is failing to capture some light showers in the low-
levels that will sweep through in the early overnight, opted to
include tempo -shra groups for FKL and DUJ where low-levels are
closer to saturation.

The main uncertainty in the forecast tomorrow will be the timing
that cigs improve. While most ensemble members have scattering
and cig rises to VFR by 18Z, save FKL and DUJ, mesoscale models
that better capture boundary layer moisture tend to hint the
maintenance of BKN/OVC decks through tomorrow afternoon in NW
flow over Lake Erie. The current forecast maintained scattering
around the 17Z to 19Z timeframe from the prior forecast for
now, but pushed back scattering at DUJ and FKL to 21Z.

.Outlook...
Ensembles favor VFR returning to the area Thursday afternoon
and staying in place thereafter. MVFR is possible on Saturday
morning for KDUJ and KLBE, however probabilities are around
30%-35%.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...Frazier/MLB
AVIATION...Milcarek