689
FXUS61 KPBZ 050531
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
131 AM EDT Sat Jul 5 2025

.SYNOPSIS...
Upper ridging and surface high pressure keep the
weather dry through the weekend as temperatures rise through Sunday.
A stalled boundary provides an unsettled pattern next week with
daily rain chances and temperatures returning back towards normal.

&&

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

- Isolated shower and thunderstorm chances mainly north of I-80
Saturday afternoon
- Heights rise and temperatures surge above 90 for much of the
  region
---------------------------------------------------------------

The upper ridge currently squarely over the Ohio Valley shifts
eastward during the daylight hours and pushes our 500 mb heights
into the low 590s. Surface high pressure slides towards the eastern
seaboard and sets up very weak southerly flow and modest warm air
advection. 850mb temperatures are expected to subtly rise to between
18-20C on Saturday. All of this will allow much of the region south
of US-422 the chance to see the mercury climb above 90 degrees (70-
80%+, near 100% in eastern Ohio).

Weak flow should allow for a lake breeze to setup off of Lake Erie
Saturday afternoon. This boundary could allow a low chance for
isolated showers or thunderstorms to creep their way off the lake
and into northwestern PA (I-80 on northward). It will likely be
tough for updrafts to punch through a cape robbing subsidence
inversion present in model soundings near 700mb, so it stands to
reason that any showers or thunderstorms that can sustain will be
rather shallow.

Activity winds down near sunset and low temperatures come up a few
degrees giving the region a warmer night than the last couple seen.

&&

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

- Dry and hot
- Heat Advisory criteria unlikely to be met
----------------------------------------------------------------

The back side of the ridge now over the eastern Great Lakes flattens
some on Sunday in response to an approaching trough. More stout
southwesterly surface and 850 mb flow will help to ramp up warm air
advection as well as mitigate any lake breeze and allow for a dry
day region wide. Skies are expected to be nearly cloud free and this
will allow for very efficient solar insolation. Accordingly high
temperatures are expected to climb once again region wide. Most
areas outside of the ridges will sport a 60%+ chance to get above 90
degrees Sunday, with pockets of 40-60% chance to strike 95 degrees
in the Pittsburgh heat island and south of I-70 in Ohio. It
continues to look like Heat Advisory criteria will not be met but
Heat Risk is expected to be Major across much of southeastern Ohio
and far southwestern Pennsylvania.

Clouds increase subtly overnight as low temperatures continue to
climb up into the low 70s for most. Warm overnight temperatures will
provide little break from the heat and can continue Major Heat Risk
into Monday.

&&

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

- Showers and storms return Monday with a chance for heavy rain
- Unsettled pattern with daily rain chances for most of the week
- Temperatures dip back to right around normal
-------------------------------------------------------------------

The upper trough arrives across the region Monday and brings with it
a weak cold front draping south from a low pressure system expected
to be in southern Canada. Continued warm air advection looks to give
us another shot at 90 degrees across much of the region (50-80%
south of I-80). Moisture advection kicks up as well and spurs our
PWATs up towards 1.5" as well as making the air feel more humid.
Modest shower coverage may occur in the morning helped along by weak
convergence but more widespread coverage of showers and
thunderstorms is expected in the afternoon helped along by daytime
heating.

Shear looks rather weak overall with model soundings indicating
somewhere near 20 knots. This could hurt our chances to see deep
organized convection but light mean wind and slow downshear vectors
parallel to the boundary suggest heavy rain may be a higher risk  as
slow moving thunderstorms grow upscale along the slowly propagating
front. Ensemble probabilities for >1" of rain remain very low at
this time but this is expected to change once we enter the high-res
window. Our entire region is currently in a Marginal Risk of
excessive rainfall from WPC.

The boundary is expected to stall somewhere south and east of
Pittsburgh on Tuesday, keeping rain chances across these areas
elevated. Behind the front temperatures will moderate some as we
move into midweek and are expected to fall near normal for the
remainder of the forecast period.

Just how far south this stalling occurs is dependent on how deep the
parent trough is, but for now ensembles peg it somewhere near the WV
ridges. Diurnal cycles Tuesday and Wednesday will likely return rain
chances, highest south and east of Pittsburgh each afternoon and
evening. A developing surface low across the Ohio Valley looks to
drag this boundary back north late this week continuing the
unsettled pattern.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...

Expect high confidence of VFR conditions at all the terminals
for the coming TAF period. Skies will remain clear overnight
with the exception of some mid and high level cloud cover along
with a few wisps of river valley fog in the predawn hours.

Heading into the day, some 4 kft to 6 kft cumulus layers are
expected with a scattered deck at FKL and DUJ. Here, an
advancing lake front may spark a few showers or thunderstorms.
The probs are low however and have left the mention out of the
FKL and DUJ TAFs as these terminals would most likely see the
development. Otherwise, expected VFR conditions with light and
variable winds through the period.

Outlook...
General VFR is forecast through Sunday with the next chance of
any restrictions or thunder mentions on Monday afternoon/evening
with the next disturbance.

&&

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

&&

$$

SYNOPSIS...MLB/AK
NEAR TERM...AK
SHORT TERM...AK
LONG TERM...MLB/AK
AVIATION...Shallenberger