415
FXUS61 KPBZ 101741
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
141 PM EDT Sat Aug 10 2024

.SYNOPSIS...
Mostly dry conditions and slightly below normal temperatures
expected through the weekend and into next week. Temperatures
begin to moderate by mid-week with rain chances possible by the
end of the week.

&&

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

- Dry and very comfortable day.
- Lows tonight a couple degrees below normal.
- Slight chance of a shower north of I-80.
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Beneath upper troughing, broad ridging extending from surface high
pressure across the Midwest has maintained a beautiful day with low
humidity and diurnal cumulus development. A westerly gradient along
with deep mixing may bring down some periodic gusts to 15 mph. Highs
will top out a couple degrees below normal this afternoon and the
cumulus field will dissipate with the loss of daytime heating this
evening.

A weak shortwave embedded in the upper troughing will move through
lower Michigan and across Lake Erie tonight. Hi res ensemble
probability for measurable precip hones in on the I-90 corridor for
best chances. Can`t entirely rule out a shower poking into our far
northern counties, but probability is low with not much moisture to
work with. Otherwise, expect a few mid-level clouds and a light west-
southwest gradient breeze with lows mainly in the mid to upper 50s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Temperatures remain a couple degrees below average.
- Dry for most but a chance of a few showers Sunday north of I-80.
-------------------------------------------------------------------

A similar story expected for Sunday as high pressure meanders
further east. The axis of the upper trough will pass overhead as
some additional weak waves move through its base. Precipitation
chances will be largely suppressed by subsidence, save for north of
I-80 where hi res ensemble probability for some scattered showers
increases by early afternoon. With cooler 500 mb temperatures
overhead in the thermal trough, some meager instability may develop
with ensemble probability for >300 J/kg of CAPE around 50-60%.
This may be enough to support a slightly higher chance compared
to Saturday for some showers north of Pittsburgh aided by the
lake breeze where inversion heights are a bit higher; thunder
chances are low with updraft heights struggling to reach high
enough for charge separation.

Headed into the coming workweek, upper troughing relocates across
New England and ensemble clusters bring weak shortwave movement
through in northwesterly flow aloft as ridging develops across the
central CONUS. With high pressure holding firm as it continues its
eastward trek, any very low precipitation chances would likely be
orographically forced or off of the lake breeze. Our residence time
on the east/northeast side of the high will maintain the below
average temperatures and low humidity through Monday night.

&&

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

- Below-normal temperatures moderate towards climatology in the
  second half in the week.
- Remaining largely dry until late week when precip chances may
  increase.
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A slightly more amplified shortwave may slide through Tuesday and
bring with it some better, but still low end, precipitation chances
along the lake breeze and the ridges which is where ensembles signal
a low-end PoPs. Subsidence should largely win out, though, and keep
the majority of the area dry with continued below normal
temperatures.

By mid-week, the upper trough will reestablish itself off to our
northeast as we remain positioned in northwest flow, but the general
trend will be for weak height rises as ensembles develop brief
shortwave ridging overhead on Wednesday and Thursday. Some
uncertainty is represented in the ensemble clusters as to the
trough`s position and amplitude with a lower probability solution
that heights are slightly higher locally which would bump
temperatures up a couple more degrees. Regardless, a trend back
toward seasonal normals is favored with high pressure in
control through at least Wednesday night. Precip chances may
pick back up to close out the week as we lose the influence of
the high and upper waves again flatten out the flow aloft as
they slide through.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
High confidence forecast in VFR today. Morning VFR stratocumulus
deck will transition to a scattered cumulus deck later this
morning, at around 6k feet. These cumulus will then dissolve
during the evening, with a mostly clear night.

Once daytime mixing commences and low-level lapse rates steepen,
gust of 15 to 20 knots out of the west are likely, mainly north
of I-70. These gusts will also diminish with sunset.

.Outlook...
General VFR is expected through the weekend as surface high
pressure builds under broad upper troughing.

&&

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

&&

$$

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