418
FXUS61 KPBZ 300457
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1257 AM EDT Mon Jun 30 2025

.SYNOPSIS...
Shower and storm activity will remain focused south of
Pittsburgh, near a stationary front. Scattered storm chances
increase tomorrow, a few storms could produce damaging winds
and/or flooding.

&&

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

- Isolated shower and/or storms will be focused south of
  Pittsburgh today
- Patchy fog possible tonight

---------------------------------------------------------------

A persistent area of low-level cumulus clouds remains over the
central part of our forecast area, tied to a stationary boundary
positioned between Morgantown, WV and Pittsburgh, PA. With
surface heating over the next 6 hours, clouds are expected to
slowly dissolve--becoming more broken and scattered opposed to
overcast.

Just south of the stalled boundary, also expected isolated showers
and/or storms south of the forecast area. The convergence
appears weak in the boundary layer with little advancement of
the front, so confidence on storm occurrence is low. However,
the terrain may help create the lift necessary to generate
isolated convection between 2pm and 7pm.

Tonight, little change is expected with temperatures dropping
into the upper 60s/lower 70s. Patchy fog will again be possible
as low-level moisture lingers, though increasing cloud cover
should keep this from being widespread. If there is fog, high
resolution models are noting areas south of Pittsburgh--likely
near the stationary boundary.

&&

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

- Strong to severe storms and heavy rainfall chances return
  Monday and Tuesday.
- Temperatures remain above-average, but below Heat Advisory
  criteria.

----------------------------------------------------------------

High pressure over the Ohio River Valley will gradually weaken
as an upstream disturbance--currently over the Great Plains--
tracks eastward over the next 24 hours within a zonal upper-
level flow. Afternoon and evening showers and storms will likely
return Monday; mainly after 12pm. Heavy downpours and damaging
wind gusts associated with downbursts will be the main threat.
Training storms, particularly over urban areas, will be the
primary concern, with isolated storms capable of producing
rainfall rates exceeding 1 inch per hour.

DCAPE values are expected to range between 400-600J/kg, through
there`s a noticeable lack of dry air below 500mb--likely a
result of lingering outflow aloft from upstream convection to
our west or southwest. However, high-resolution models indicate
an increase in mid-level shear (800mb-700mb) between 19Z to
23Z, which could support stronger updrafts.

On Tuesday, a cold front and accompanying trough moving through
the Ohio River Valley will likely trigger organized showers and
thunderstorms. With a tropical airmass in place, heavy downpours
are expected. However, increased vertical wind shear should help
storms move quickly, reducing the flood risk. The Storm
Prediction Center (SPC) has placed areas east of the PA/WV
ridges under a Marginal Risk. If the front slows down, the
threat for severe storms could expand into western Pennsylvania
and northern West Virginia.

&&

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

- Cold front Thursday brings back showers and storms.
- July 4th holiday looks dry.
- Rain chances return late next weekend.
-------------------------------------------------------------------

A shortwave will churn through the ECONUS longwave trough on
Thursday and kick a cold front through the area from the northwest.
Timing remains a bit uncertain, but passage is likely some time on
Thursday which will return the chance for showers and storms. Dew
points ahead of it look to sit in the low 60s with not much return
flow on Wednesday, but the NBM prob for >1000 J/kg SBCAPE is around
40-50% in the afternoon hours. Deep layer shear may be the lacking
component with the best forcing and flow displaced to the north with
the shortwave. Still, machine learning does peg at least a low-end
chance of severe weather with the passage, contingent on it being at
a favorable diurnal time.

Headed into the fourth, ensembles are in good agreement on a return
of mid-level ridging behind the departing longwave. Some subtle
timing differences arise with how quickly the ridge builds which
suggests that high temperatures are lower confidence right now as
supported by the NBM MaxT spread of 6 degrees at PIT. Rain chances
are low in any scenario at less than 20% with dry air advecting in
in the wake of Thursday`s boundary.

The ridge flattens out into the weekend with a mid-level zonal flow
pattern taking over. Ensembles do agree on low pressure development
across the Northern Plains sometime Friday into Saturday and quickly
sliding east, but disagreement on timing lends low confidence
precipitation chances locally as the attendant surface cold front
follows along with it. Most of Saturday looks dry at this time with
even the faster solutions holding precip chances off until early
Sunday, so most likely will see a more unsettled pattern return for
the latter half of the weekend and into next week. Temperatures
around average through the second half of the week may warm to
slightly above average for the weekend.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR is expected tonight as mid and high level clouds cigs
continue ahead of an approaching shortwave trough. CU rule and
model soundings indicate a diurnal cumulus layer will develop by
mid to late morning as convective temperatures are reached.

Numerous showers and thunderstorms are expected to develop by
early to mid afternoon as a shortwave trough crosses the Upper
Ohio Valley region, and as a surface boundary lifts north. CAPE
is expected to range from 1000-2000 j/kg as the wave crosses,
with 0-6km shear near 40kt. Included TEMPO for thunderstorms at
all airports for the most likely time of occurrence, with PIT
generally 19Z-23Z. Included MVFR restrictions for now, though
IFR will be possible in locally heavy rainfall.

Convection should gradually wane this evening with the loss of
diurnal instability, and as the shortwave exits.

Outlook...
Fog and stratus restrictions are possible tonight with low level
moisture in place. A crossing cold front will result in numerous
showers and thunderstorms again on Tuesday afternoon and
evening. VFR returns Wednesday under high pressure, before
restriction and thunderstorm potential returns with a Thursday
cold front. VFR is expected again by Friday under high pressure.

&&

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

&&

$$

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