179
FXUS61 KPBZ 200554
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
154 AM EDT Wed Aug 20 2025

.SYNOPSIS...
Scattered shower and thunderstorm chances will return tonight
and Wednesday with a weak cold front. After seasonable
temperatures Wednesday, highs will gradually warm into the
weekend.

&&

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

- Cold front brings scattered showers and storms tonight
- Mild overnight lows
---------------------------------------------------------------

Ongoing broken clusters of showers and storms are progressing
across central Ohio this evening along an eastward moving cold
front. MLCAPE values have reached up to 2000 J/kg with 15-20
knots of effective shear along the line, though it has struggled
to gain a lot of strength thus far. Mid-level lapse rates are
poor and forcing aloft is displaced just behind the front. Locally,
we`ve had a hard time even popping much cu today with drier air
both at the surface and mid-levels represented on latest ACARS
soundings from PIT.

Instability is progged to increase per the latest RAP as the
front gets into our eastern Ohio counties around 7-8pm, but by
that time, we`re going to be losing daytime heating and there`s
some question how well these storms will hold together both due
to the time of day and extent of dry air locally. It`s likely
that elevated instability will support maintenance of them as
they move across our area and into western PA by 10-11pm, but
any severe threat should be on the downward trend by that time.
Some 30-40 mph gusts and lightning should be the primary
threats for our area, but can`t entirely rule out a stronger
storm with highest probability in eastern Ohio especially if
cold pools can congeal.

Otherwise, lows will be a bit above normal with mostly cloudy
skies.

&&

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

- Scattered shower/storm chances return tonight and Wednesday.
- A few higher terrain showers possible Thursday afternoon.
----------------------------------------------------------------

Scattered rain chances will increase overnight ahead of the trailing
cold front, dissipating in the wake of the front by Wednesday
afternoon/evening. Upslope showers across the ridges may linger
through the afternoon.

All indications are that precipitation will be widely scattered,
with some locations receiving very little rainfall. Probability for
total rainfall of >0.25" remains at 60% or lower, with highest
values in Mercer, Venango, and Forest counties. Still, modeled PWATs
for Wednesday morning are anomalously high and range from 1.8 to
2.0". Though unlikely, if deeper convection is able to develop,
localized flash flooding can`t be ruled out.

Renewed high pressure across the Great Lakes and Ohio Valley should
keep most of the area dry overnight into Thursday. Some weak
troughing could help to initiate stray diurnal showers primarily
over the ridges Thursday afternoon. With Hurricane Erin to our east,
flow will be out of the northeast on Thursday.

&&

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

- Above average temperatures expected into the weekend
- Precipitation chances return Saturday into Sunday with a
  passing cold front
- Cooler weather begins next week.
-------------------------------------------------------------------

Extended forecasts indicate that a ridge of high pressure over
the Ohio River Valley will be present into Friday, bringing
mostly dry conditions and temperatures that are near to above
average.

A passing cold front and an upper-level trough will likely
increase the chances of precipitation Saturday into Sunday, but
rainfall amounts look low this far out. NBM PQPF for >0.25"
range from just 30%-40% for counties along the Appalachian
ridge-line and less than 25% chance west of Pittsburgh. Of note,
machine learning does indicate a 5% to 15% chance of severe
weather with this passing front on Sunday, so this will need to
be monitored in the coming days.

Generally high confidence exists in persistent eastern CONUS
troughing by early next week. This should keep temperatures
below average during the first half of next week.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Broken line of showers and the occasional rumble of thunder
continues to cross the area early this morning in advance of a
cold front. Given less favorable environment, and little
lightning remaining, have removed mention of thunder for the
remainder of the overnight period. A period of low MVFR to IFR
ceilings is expected following frontal passage, impacting most
terminals by 14z. Cigs should then lift through the day with
mixing, though a few afternoon showers/tstms are possible with a
secondary shortwave as it drops SEWD across the region. This
secondary rain chance should dissipate through the evening
hours.

Low-level moisture tonight will allow stratus and fog through
Thursday morning.

Outlook...
VFR is then expected to return Thursday afternoon under high
pressure until the approach of a Sunday cold front.

&&

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

&&

$$

SYNOPSIS...Rackley
NEAR TERM...MLB
SHORT TERM...Rackley/Lupo
LONG TERM...Rackley/Lupo
AVIATION...WM/Rackley