512
FXUS61 KPBZ 111654
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1254 PM EDT Mon Aug 11 2025

.SYNOPSIS...
Dry and hot weather is expected through early Tuesday under
high pressure. Scattered afternoon showers and thunderstorms
return Tuesday through Thursday with the best chance on
Wednesday. Temperatures remain above normal through this week.

&&

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

- Dry with increasing heat
---------------------------------------------------------------

High pressure still centered off the Mid-Atlantic under an expansive
mid-level ridge across the eastern CONUS continues to support dry
weather today. Modest warm advection with southerly flow in the low
levels will bump 850 mb temperatures to the 17-19C range, a bit
higher than Sunday. Thus, highs should be a touch warmer today in
the upper 80s with low 90s in the urban areas and valleys. Heat
indices will remain below advisory criteria with low to mid 60s dew
pints, but it`ll certainly feel warm and muggy out there today. Warm
air in the mid-levels will cap any updraft attempts, but with a
convective temperature of 83F off of our 12z balloon, expect
diurnal cumulus will develop shortly after noontime before
dissipating with sunset.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:

- Warmer Tuesday with some isolated showers/storms
- Better chance of storms on Wednesday
----------------------------------------------------------------

The first half of Tuesday is likely to be dry across the board as
ridging begins to break down ahead of an approaching trough and
surface high pressure meanders farther east. Several of the latest
CAMs try to develop some showers/storms in the afternoon, but
forecast soundings within them all still suggest some degree of
capping with a warm layer ~600 mb. Forcing will be weak at best,
with the strongest courtesy of orographics and the lake breeze, so
expect that coverage likely maximizes along those sources though
still remains scattered. Outside of that, some showers will likely
be able to develop, but it`s more likely in any case that we`ll
struggle to get a lot of deep convection. In a lower probability
case that the warm layer isn`t quite as pronounced, can`t rule
out a stronger storm with gusty wind potential given elevated
DCAPE, 750-1250 J/kg MLCAPE, and weak deep layer shear.

Gradient flow won`t enhance much ahead of approaching low pressure
and an associated boundary, so not expecting notably strong
deep warm, moist advection out ahead of it. Still, dew points
will climb back up into the mid to upper 60s with highs favored
to reach 90 for a good portion of the area, especially south of
I-80. The resultant combination of heat and humidity will be
AppTs in the mid to upper 90s. A few locales in urban areas and
valleys could nose their way to near 100F heat indices, but
don`t see it being widespread and any showers/storms would
suppress that threat. Lows only dipping into the upper 60s/low
70s Tuesday night with the warm daytime will bump the heat risk
up to moderate to locally major on Tuesday, so those who are
sensitive to heat should consider reducing their time outdoors.

Wednesday brings a higher chance for better coverage of afternoon
showers and storms with better forcing from the passage of a cold
front and supporting shortwave energy. Probability for >2000 J/kg
SBCAPE reaches 40-70% by afternoon though shear remains weak with
the belt of strongest mid-level flow displaced to our north in
closer proximity to the low. Some mid-level dry air should be in
place to enhance DCAPE values and downburst potential in stronger
storms with ensemble mean values around 800 J/kg. PWAT values
increase as well to 1.5-1.75" suggesting some heavy downpours within
any storms with weak flow/slow storm motion (corfidi upshear vector
~10 knots), but the flooding threat will be low and mostly tied to
urban areas given dry antecedent conditions. Increased cloud
coverage and precip on Wednesday will keep highs in check and lower
heat indices.

&&

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

- Lingering showers and storms Thursday before drier weather returns
  headed into the weekend
- Temperatures still remain above normal even behind the front
-------------------------------------------------------------------

Still some uncertainty how quickly Wednesday`s boundary exits the
area as ensemble members suggest another mid-level wave passing
through Thursday. The front doesn`t look to be in a hurry to exit,
so this could keep some showers and storms in the forecast for
another day with highest coverage along the boundary. By the latter
half of the day, flow should amplify just a bit and flip
northwesterly which will kick the front out of the area.

Looks like we`ll get a brief reprieve from the mugginess with lower
dew points working in on Friday in weak northerly/westerly flow.
Ensembles suggest high pressure building in behind the front which
should return dry weather into the weekend, save some upslope
chances Friday and Saturday afternoons. Longer range guidance
suggests that moisture kicks back up over the weekend as
temperatures do the same, so a return of the heat and humidity is
favored headed into next week.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Confidence remains high that VFR conditions will prevail for all
TAF sites. Surface heating has prompted SCT to FEW diurnal
driven cumulus between 4-6kft. Winds will be general light to
variable from the south. Clouds will dissipate after sunset.
Probability of fog is low and will be isolated to river valley
areas south of PIT; impacts to terminals are very low.

Outlook...
Isolated showers may develop after 18Z on Tuesday ahead of an
approaching trough. However, confidence is low for impacts to
terminals.

The best chance for rain will Wednesday afternoon and evening as
the trough advances just north of the region. Showers and
thunderstorms will be likely in the vicinity of a number of
terminals. Gusty winds and heavy downpours may occur.

A downward trend in rain potential is favored to end the week
as high pressure develops near New England.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...Hefferan