989
FXUS61 KPBZ 222358
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
758 PM EDT Fri Aug 22 2025

.SYNOPSIS...
Near-seasonable temperature and dry conditions will persist thru
tonight amid high pressure. Precipitation chances return this
weekend with a crossing frontal system. Temperature will warm
Saturday ahead of the front, but will trend cooler next week in
its wake.

&&

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

- Dry conditions and slightly above-normal temperature
---------------------------------------------------------------

Shortwave ridging remains overhead tonight but will begin to
break down as an unseasonably strong closed low in central
Canada impinges on the Great Lakes region. Surface high pressure
gliding east is now centered off in that direction and will
continue pushing offshore ahead of the approaching low but keep
dry weather in place overnight tonight; a few mid-level clouds
will stream by with light wind and low temps just slightly
above climatology.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
KEY MESSAGES:

- Precipitation chances return Saturday into Sunday with a
  passing cold front
----------------------------------------------------------------

A highly predictable pattern will persist thru the weekend,
lending higher confidence in the evolution of weather thru Sun
night.

Stronger flow aloft will be shunted SW`ward into the Great
Lakes region as a Canadian closed low continues SE`ward,
advancing a cold front across the region Sat night and Sun.

Temperature will continue around seasonable values over the
weekend as general swly flow maintains the advection of warm,
moist air into the region ahead of the impending mid-level
trough.

Sat will see development of modest MUCAPE (500-800 J/kg) amid
this warm-advection regime, but ascent will be tied mainly to
orographic lift, thus focusing updraft formation tied especially
to the terrain of the ern zones from Indiana County PA SW`ward
to Tucker County WV.

Broader convective coverage appears to hold off until Sun.
Within the right-entrance region of a mid-level jet streak,
there appears higher likelihood of the presence of 500-1000 J/kg
MUCAPE on Sun afternoon as the cold front nears the upper Ohio
Valley.

PWATs are not projected to be exceptionally high by Sun (around
1.2 - 1.4"), even at the LREF-TLE clusters` 90th percentile. So
although showers and storms are likely along and ahead of the
cold front, any impacts from excessive rainfall likely will be
limited, given faster storm motion and standard efficiency of
rainfall.

Machine-learning projections of severe-weather and flash flood
potential also do not favor a notable risk, with which we concur
at this time based on limited evidence for development of steep
lapse rates/a high-DCAPE environment despite increasing shear
and buoyancy sufficient for deep, moist convection.

&&

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

- Cooler weather during first half of next week: highs in the
  70s and lows in the 50s
- On Tuesday, rain showers are possible with northwesterly flow
  off the Great Lakes
-------------------------------------------------------------------

Unusually high confidence in the weather pattern persists thru
much of the coming week, as ridging amplifies in the wrn CONUS
and broad troughing lingers in the ern CONUS.

Primary variances related to the broad pattern are tied to the
eventual amplitude of the CONUS-scale ridge/trough pattern and
potential for a shortwave trough to advance through the nwly
flow aloft into the Great Lakes region near Wed/Wed night.

No matter how amplified the pattern eventually becomes, a cool
airmass will be invading the region by Mon, with temperature
more typical of mid Sept. than late Aug.

The cooler airmass arriving post-cold front is highly likely to
support the development of lake-effect showers Tue/Wed as the
temperature delta between the water and H85 temp will be
sufficient for deeper convective updrafts. Given the projected
reasonable range of wind directions at this timeframe, the reach
of these showers appears limited to areas near and north of
I-80, with lesser coverage south from the interstate.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Mostly dry weather with VFR conditions will persist through the
current TAF period as high pressure remains in control.

Tonight wind will become light and variable after sunset with
at most a few mid-level clouds. Headed into tomorrow, another
diurnal cu layer is expected to develop with SCT to BKN coverage
around 4-6kft. A few showers/storms are possible after 20z but guidance
suggests coverage will be widely scattered with low probability
to impact any given terminal. Highest probability lies at
FKL/DUJ/LBE so have included a PROB30 for TSRA. Wind outside of
any precipitation will also pick up a bit tomorrow afternoon to
7-10 knots out of the southwest as the gradient tightens.

.OUTLOOK...
Higher chances of showers/storms arrive with a Sunday cold front
along with increased chances for ceiling restrictions. Subsequent
upper-level troughing and cool air aloft could result in patchy cig
restrictions north of PIT Monday and Tuesday along with a few
scattered showers.

&&

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

&&

$$

SYNOPSIS...Kramar
NEAR TERM...Kramar/MLB
SHORT TERM...Kramar
LONG TERM...Kramar
AVIATION...MLB/Lupo