628
FXUS61 KPBZ 162350
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
750 PM EDT Tue Jul 16 2024

.SYNOPSIS...
Severe potential south of I-70 early this evening will be
followed by another risk for storms late tonight. Thereafter, a
cold front will swing through, allowing a third and final chance
of severe weather tomorrow. Damaging winds remain the primary
threat. Seasonable weather will prevail Thursday and Friday
before a weekend warm-up.

&&

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

- Two independent chance of severe weather are possible late
  tonight and tomorrow afternoon (through Pittsburgh and points
  south and east).
- The primary threat remains damaging winds.

__________________________________________________________________

.. Evening update ..

The last of the rain is moving out of the far southern ridges.
Models are not hinting at much more activity until late tonight
early Wednesday morning. An isolated shower can`t be completely
ruled out, but with the sunsetting and no real good forcing
until later tonight, it does not look likely. PoPs were updated
to capture a quiet rest of the evening. Overnight temperatures
and clouds were also updated with the latest hires guidance.

.. Previous Discussion ..

Save a brief reprieve behind the passing wave late this evening
through the early overnight, another embedded weak low-to-mid
level wave will pass in the flow overnight. This time,
probabilities of at least 20kts of bulk shear are 20% to 40% in
the I-80 corridor, and less than 20% elsewhere. CAPE will likely
be in the hundreds and mostly elevated, but should any mature
updraft develop, it will again be possible at collapsing into
gusty winds at the surface, pending breaking a shallow surface
inversion. The most likely time for this event will be around
4am to 8am. This remains the lowest probability of the three
severe chances.

Last, but not least, severe probabilities increase into the day
tomorrow along and ahead of the passing cold front. With better
synoptic forcing and an increasing gradient within the trough
itself, the confidence in initiation is the highest in this
period. Consequently, bulk shear probabilities increase to 50%
to 60% of greater than 30kts, and CAPE will be in the 500 to
1500 J/kg range, but mid level dry air will drop off, decreasing
downburst threats. Convective nature will resort to higher
confidence in storms, but lower confidence in intensity. Current
thinking reflects that damaging winds are still the primary
threat from noon to 8pm with a secondary threat of hail.

&&

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

- A drier and cooler period will ensue through Thursday and
  Friday.

_________________________________________________________________

Dependent on front progression speed, some storms may linger
into the mountains of northern West Virginia in the early
overnight period, but thereafter, dry conditions are favored.
Low-level cold and dry advection will keep temperatures near or
even a few degrees below average Thursday and Thursday night
with valley fog chances.

Stout mixing into the day on Friday under high pressure will
result in temperatures near normal, and fairly low humidity.
This will leave the area feeling comfortable for the last day of
the work-week. Radiative cooling will also drop temperatures
near normal.

&&

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

- Diurnal shower/storm chances increase slightly with increased
  moisture.
-------------------------------------------------------------------

Rising heights Saturday/Sunday in response to increased
troughing over the Central Plains may bring moisture back from
the south, leading to increased diurnal precipitation chances,
mainly southeast of Pittsburgh. This will also result in a
warming trend through the weekend.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
The convection threat is largely over for the evening. A few
isolated showers are possible mainly southwest of PIT this
evening, but VFR conditions are expected to dominate at all TAF
sites through the evening and into the early overnight period.

Showers and a few embedded thunderstorms remain possible once
again after 10Z or so, as a few hi-res models show development
from the southwest. Ensembles continue to show high
probabilities for MVFR ceilings arriving with this activity,
with a period of IFR also possible mainly north of PIT. These
ceilings will slowly lift as daytime mixing increases, possibly
achieving low VFR by early afternoon. Another round of more
concentrated showers and thunderstorms then arrives with a
crossing cold front. Thunder timing remains problematic, and
thus stuck with VCTS mention for now. These storms will be
capable of brief IFR/LIFR visibility in downpours, as well as
strong, variable wind gusts. Terminals northwest of PIT will be
cleared by the cold front prior to 00Z, with a wind shift to
northwest and breaking clouds.

.Outlook...
VFR returns Thursday through Saturday under building high
pressure.

&&

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

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...Milcarek
LONG TERM...CL/Milcarek/88
AVIATION...Cermak/WM