972
FXUS61 KPBZ 052313 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
713 PM 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 SUNDAY/...
KEY MESSAGES:

- Isolated showers and thunderstorms possible mainly north of
  I-80 late this afternoon.
- Quiet overnight with low temperatures trending warmer than
  the past few nights.
---------------------------------------------------------------

Since forecast with no weather mentioned is inconsistent with
our intended message of isolated showers/storms in vicinity of
I-80 corridor as well as from Pittsburgh to Latrobe to Uniontown
(especially ridge lines), made an update to near-term PoP grids
to reflect this intended message. Previous discussion follows...

Convection wanes and the cu field dissipates after sunset with
the loss of daytime heating. Quiet weather is expected overnight
with low temperatures remaining in the mid to upper 60s, a few
degrees above seasonal norms.

&&

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

- Building heat through Sunday and Monday. Those sensitive to
  heat should take proper precautions.
- Showers and storms return Monday.
----------------------------------------------------------------

Ridging will start to break down and turn flatter on Sun in
response to an approaching trough from the Great Lakes. Stronger
warm and moist advection will ensue as sly low-level flow
strengthens a bit, which will also mitigate a lake breeze and
keep the day dry across the board. Subsidence and a dry column
will allow for efficient insolation, and it will be hot with an
80-90+% chance of highs reaching 90F in the lowlands and a
60-70% chance in the ridges. Combined with increased dew points
in the mid to upper 60s, heat indices will top out in the upper
90s. Heat Advisory criterion doesn`t appear to be reached, but
that doesn`t mean that heat impacts are null, as the Heat Risk
jumps up to major category with compounding days of 90s heat
indices and low temperatures only in the 60s and low 70s. Those
especially susceptible to heat-related effects should take
proper precautions.

Clouds increase subtly overnight Sun as lows continue to hold
quite warm in the low 70s for most. Warm overnight temperature
will provide little break from the heat and continue Major Heat
Risk into Mon.

The upper trough arrives across the region Mon and brings with
it a weak cold front draping swd from a low pressure system
expected to track across srn Canada. Continued warm-air
advection looks to give us another shot at 90F across much of
the region (50- 80% south of I-80). 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 with diurnal heating trends.

Shear looks rather weak overall with model soundings indicating not
more than 15-20 knots deep-layer. This could hurt our chances
to see deep, organized convection but support a heavy rain
threat. Column moisture increases and spurs our PWATs up towards
1.5" with light cloud bearing-layer wind and slow downshear
vectors oriented parallel to the boundary, which all suggest a
potential flooding threat as slow-moving thunderstorms grow
upscale along the front. Ensemble probabilities for >1" of rain
remain very low at this time, but that`s likely to change once
we get the hi-res guidance in. Our entire region is currently
in a Marginal Risk (1/4) of excessive rainfall from WPC.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Unsettled pattern next week with daily rain chances along a
  stalled boundary.
- Temperatures stay near normal.
-------------------------------------------------------------------

The boundary is expected to stall somewhere south and east of
Pittsburgh on Tue, keeping rain chances in the forecast well
into next week, highest south of Pittsburgh in proximity to the
boundary. Behind it, temperature will moderate some as we move
into mid-week and are expected to fall back to near normal for
the remainder of the forecast period.

Just how far south the front stalls is dependent on how deep the
parent trough is, but for now, ensembles peg it somewhere near
the WV ridges. The highest coverage and probability of precip
will be in the afternoon and evening coincident with diurnal
trends, highest south and east of Pittsburgh. Deep-layer
moisture will remain elevated with ensemble PWAT values in the
range of 1.25-1.5", so any showers and storms will likely be
efficient rainfall producers. A developing surface low across
the Ohio Valley looks to draw the boundary back nwd late this
week, continuing the unsettled pattern and increasing rain
chances across more of the area.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
High confidence of prevailing VFR conditions at all terminals
through the TAF period. Any lingering cu has a high likelihood
of dissolving with loss of heating, and overall clouds thru the
night will be limited, and mainly in the form of cirrus.

Deep boundary-layer mixing is on tap to resume on Sun. Given
weak deeper wind field, gusty wind does not seem likely but
ought to become prevailing light out of the southwest. However,
a modest afternoon cu field 6-7kft could result for a few hours
starting around 17Z. Like today, the afternoon cu would be
expected to erode as heating wanes.

Outlook...
Daily thunderstorm chances (and associated restrictions) return
Monday through the coming week, likely following a diurnal
pattern with peak probabilities occurring each afternoon and
evening.

&&

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

&&

$$

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