378
FXUS61 KPBZ 040522
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
122 AM EDT Fri Jul 4 2025

.SYNOPSIS...
A trough will drop south into the area bringing a
chance of unsettled weather today. Starting Friday, the region will
be under the influence of high pressure through the next few days.
Fog development is possible during the morning each day. On Monday,
an unsettled pattern will return to the region.

&&

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

- Isolated showers and thunderstorms.
- Mainly river valley fog expected tonight.
---------------------------------------------------------------

Some very isolated showers have been observed south of
Pittsburgh this evening, through ACARS soundings show evidence
of a mid level cap with plenty of dry air overhead threat
should limit mature updraft development. This has kept updrafts
largely less than 10kft. With a less favorable environment
expected into the overnight, the severe risk is over with any
lingering showers fading beyond sunset.

Once again, surface dewpoints are running below the NBM
forecast, agreeing with the assessment that any fog overnight
should be limited to river and sheltered creek valleys.

.. Previous Discussion ..

The tail end of a cold front is expected to move through the
northern counties of Pennsylvania starting this afternoon bringing a
round of showers and thunderstorms to the area. The NBM gives a 25%-
30% chance of thunderstorms for this area. The timing for the
potential will be between 3PM and 8PM. The probability for SB CAPE
of 1000 J/kg is about 60%-80% as the front moves through the area.
This combined with an elevated dry air mass brings in a Marginal
Risk for wind for PA counties along the Appalachians.

Heading into the overnight, a lingering shower or storm can`t be
ruled out. High pressure will take over again with clearing skies
tonight and easing the winds. With calm wind and clear skies,
there is a potential for fog, impacts are mainly expected in
river valleys with the warm water and cooler air temperature.
Low temperatures are expected to be slightly below normal.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
KEY MESSAGES:

- Dry and sunny weather for the Fourth.
- Chance for fog on Friday and Saturday mornings.
- Temperatures above average.

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

Surface high pressure and ridging aloft should promote mainly dry
and warm weather again Friday and Saturday. The highs for Friday
will only make it into the mid 80s.

Rising heights and southerly flow on Saturday should boost area
highs into the upper 80s to near 90F. NBM probs for 90F are highest
across eastern Ohio, northern West Virginia panhandle, and the
Pittsburgh urban heat island (65%-85%). For Lawrence, Beaver,
southern Armstrong, and northwestern Westmoreland counties,
probabilities for 90F are generally around 30%-40%. Outside of these
regions, the probability for these temperatures are lower with no
chance in most of the areas along the Appalachian Mountains.

On Sunday, the ridge is forecast to flatten with westerly flow aloft
across the Upper Ohio Valley region. The 500 mb heights are expected
to approach 590 dam, maintaining hot conditions across the region.
There is a high probability across most of the region (75%-95%) that
maximum temperatures reach or exceed 90F. The heat indices remain in
the 90s, so there is a low chance for a Heat Advisory being
issued.

&&

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

- Shower and thunderstorm chances returning Sunday night and Monday.
- Increasingly hot and humid conditions on Monday
- Post frontal rain chances remain on Tuesday and Wednesday.
-------------------------------------------------------------------

With the flattened ridge, disturbances embedded in the flow aloft
are expected to periodically cross the region, with daily shower and
thunderstorm chances returning.

On Monday, 500 mb heights are still expected to be around 590 dam,
allowing hot and humid conditions to persist across most of the
region. High probability (60%-75%) of maximum temperatures at or
above 90 degrees. The chances of Heat Advisory criteria remains low
as heat indices remain in the 90s.

Temperatures are expected to relax for the Tuesday and Wednesday
period due to the passage of a cold front Monday night. This will
allow cooler air into the region with the potential of some
lingering chances for precip behind the front. There is a lack of
confidence with this pattern.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Largely clear skies and VFR is expected to prevail through the TAF
period.

Minimal fog impacts are expected overnight with efficient dewpoint
mixing seen this past afternoon. River valleys seem the most likely
culprits Friday morning. Have maintained TEMPOs for MGW and HLG but
lessened impacts to high end MVFR. Added a TEMPO for FKL following
the same line of thinking.

A scattered VFR cu field will sprout tomorrow during daytime
heating but clouds will once again dissipate as the sun sets. Light
and variable winds are expected to become northerly but remain
rather light tomorrow afternoon before once again relaxing in the
evening.

Outlook... VFR is expected through Sunday as high pressure moves
across the region. Precipitation chances and isolated restrictions
return Sunday night into Monday.&&

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

&&

$$

SYNOPSIS...Shallenberger/Lupo
NEAR TERM...Milcarek/Shallenberger/Lupo
SHORT TERM...Lupo
LONG TERM...Shallenberger/Lupo
AVIATION...AK