794
FXUS61 KPBZ 232338
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
738 PM EDT Sat Aug 23 2025

.SYNOPSIS...
Isolated showers and storms are anticipated east of Pittsburgh
tonight and tomorrow as a cold front approaches and passes
through the region. A prolonged cool pattern is expected to set
in beginning Monday.

&&

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

- A weak trough will bring isolated showers/storms along the
  ridges
---------------------------------------------------------------

Isolated showers and storms continue this evening along the PA
and WV ridges where orographic ascent and a noted area of
convergence along the Laurels is aiding in development.
Locally, our 00z balloon and recent ACARS soundings from PIT
suggest a suboptimal convective environment with a lot of warm
air in the mid-levels stunting updraft growth potential.
Mesoanalysis depicts a sharp cutoff in MLCAPE values along I-70
(<500 J/kg to the north and 1000-1500 J/kg to the south).
Farther south, a bit less warm air and repeated updraft attempts
have been allowed some deeper convection to be successful in an
environment with >1000 J/kg of DCAPE. As a batch riding up the
WV ridges to our south moves north and into our WV counties
around 8-9pm, there stands a low probability chance that a
stronger storm could put down some gusty wind given the high
DCAPE environment.

Some CAMs still suggest some reinvigoration after midnight with
another band of low-level convergence across southwest PA and
northern WV, but these shouldn`t pose a severe threat given poor
diurnal timing. With lingering low-level moisture, very patchy
fog is possible to develop in river valleys and especially wherever
any rain falls tonight, but warmer overnight lows and light wind
should preclude development more than previous nights.

&&

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

- Seasonable temperatures expected ahead of a cold front
- Shower/storm chances remain elevated
----------------------------------------------------------------

Temperatures will continue to roam around seasonable Sunday as
southwesterly flow maintains the advection of warm, moist air
into the region ahead of the approaching mid-level trough.

PWATs are not projected to be exceptionally high (around 1.2 - 1.4")
with values expected to peak in the morning and decrease throughout
the day as wind gradually veers out of the west by Sunday evening.
Showers and storms along/ahead of the cold front will have faster
storm motion and standard efficiency of rainfall. So, any impacts
from excessive rainfall will likely be limited.

Machine-learning projections of severe-weather and analog guidance
continue to show a low likelihood of severe potential Sunday with
the crossing low pressure system.

Chances for precipitation will start early Sunday afternoon,
extending from eastern Ohio northeastward to north/central
Pennsylvania. After sunset, the chance for showers will remain
against the Appalachian ridge-line in western PA and northern
WV. Before midnight the chance for rain in these areas will
gradually decrease through early Monday morning.

&&

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

- Cooler weather during first half of next week.
- On Tuesday, rain showers are possible with northwesterly flow
  off the Great Lakes.
-------------------------------------------------------------------

High confidence in the weather pattern persists through much of the
coming week, as ridging amplifies in the W`rn CONUS and broad
troughing lingers in the E`rn CONUS.

By Monday, a cool airmass will be invading the region with daytime
temperatures in the low 70s and nighttime temperatures in the low
50s/upper 40s. This cooler airmass is highly likely to support the
development of lake-effect showers Tue/Wed. The northwesterly flow
along with the temperature difference between the water and 850mb
temperatures will create instability over the Great Lakes. This will
result in lake-effect rain shower development. Given the projected
reasonable range of the wind at this timeframe, these showers are
likely to be limited to areas near and north of I-80, with lesser
coverage south of the interstate.

Later in the week, variances related to the broad pattern are tied
to the eventual amplitude of the CONUS-scale ridge/trough pattern.
There is the potential for a shortwave trough to advance through the
NW`ly flow aloft into the Great Lakes region around Wednesday
evening.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Most TAF sites remain VFR tonight with light wind as a mid-
level cloud deck moves overhead. Some showers/storms will be
riding up the ridges into the overnight hours with highest
chance, but still low, for impacts to MGW/LBE in tandem with the
strongest convergence/orographic ascent. Represented this with
a TEMPO for TSRA at both sites but it`s possible that that could
even be overdone depending how these storms survive the next
couple hours as they push north out of central WV. MGW may see
some fog toward daybreak, especially if it rains overnight, but
any additional fog development will be spotty at best with
overnight lows trending a bit warmer.

Storm chances return again Sunday afternoon with a cold front;
cig and vis restrictions are likely with any storm that impacts
a terminal, but again confidence on timing and spatial impacts
remains low at this juncture. Gradient wind picks up to 5-10
knots out of the west/southwest by late morning.

.OUTLOOK...
Cool air aloft could result in patchy MVFR cig restrictions
north of PIT Monday and Tuesday along with isolated lake
enhanced showers.

&&

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

&&

$$

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