PBZ issues Area Forecast Discussion (AFD) at Aug 23, 7:55 AM EDT494
FXUS61 KPBZ 231155
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
755 AM EDT Sat Aug 23 2025
.SYNOPSIS...
Precipitation chances return this weekend with passing low
pressure and associated cold front. Temperatures will warm
today ahead of the front, but much cooler air is expected to
build in its wake and linger through next week with a drier
pattern in place.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- An approaching front returns scattered showers/storms today
primarily south and east of Pittsburgh.
- Highs will trend up slightly, several degrees above normal.
---------------------------------------------------------------
Surface high pressure migrates off to the east today downstream of
an approaching low sliding across the Great Lakes. This will
bring largely dry conditions across the region with latest
ensemble guidance showing single digit 1hr PoP chances, until
increasing later this evening into the 20-40% range largely
to the south and east of PGH where model soundings show low
level inversions being overcome by the increased surface
instability. Coverage should be isolated to scattered in nature
with the warm mid- levels and generally weak forcing precluding
any stronger storms.
As the pressure gradient tightens up today we will see
increased moisture advection with enhanced southwesterly lo
level flow, pushing dew points back into the upper 60s. Daytime
highs will move up to the mid/upper 80s. PWAT values reach up
to 1.1-1.25" overnight with continued southwesterly flow. MUCAPE
in this moist environment could support some heavy downpours,
but given the relatively dry antecedent conditions, flash
flooding will be a low threat and really should be primarily
tied to urban areas that see repeated rounds of heavy rain in a
short period of time.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Shower/storm chances continue Sunday with a passing cold
front
----------------------------------------------------------------
Temperatures will continue to roam around seasonable values
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"), even looking 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 analog
guidance continue to show a low likelihood of flash flood or
severe potential Sunday with the crossing low pressure system.
&&
.LONG TERM /MONDAY 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
-------------------------------------------------------------------
High confidence in the weather pattern persists though 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 /12Z SATURDAY THROUGH WEDNESDAY/...
VFR will prevail as fog lifts/dissipates. Cu/stratus will
linger around 4-6kft. The mid- level cloud deck will thicken
late in the day and showers/storms are possible after 20z
through sunset with then another round on either side of
midnight. Guidance suggests coverage will be scattered with low
probability to impact any given terminal. Highest probability
lies at MGW/LBE in tandem with the strongest
convergence/orographic ascent, so have included a TEMPO there
and PROB30s elsewhere save ZZV. Wind will increase to 7-10
knots out of the southwest as the gradient tightens with the
approaching front.
.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...88
NEAR TERM...MLB/88
SHORT TERM...Kramar/88
LONG TERM...Kramar/88
AVIATION...34
Source:
PBZ issues Area Forecast Discussion (AFD) at Aug 23, 7:55 AM EDT---------------
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