978
FXUS61 KPBZ 291658
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1258 PM EDT Sun Jun 29 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 /THROUGH TONIGHT/...
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 /MONDAY 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 SATURDAY/...
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 /16Z SUNDAY THROUGH THURSDAY/...
MVFR/IFR clouds expected to dissolve between 17Z to 19Z with
surface heating.

The boundary may stall near the Mason-Dixon Line through Sunday,
keeping a few stray showers and perhaps a thunderstorm in the
area, with MGW having the best chance of seeing impact. For now,
Put a PROB30 in for MGW as a thunderstorm can`t fully be ruled
out.

For the most part, expect light winds through the rest of the
TAF period with mainly dry conditions. Cloud cover will be
mainly cirrus passing through the area. A chance of fog will be
possible again on Sunday night.

Outlook... Showers/storms return again Monday as the boundary
lifts back north as a warm front. Rain and restriction chances
continue into Tuesday, before a cold frontal passage returns VFR
conditions for Wednesday and Thursday.

&&

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

&&

$$

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