938
FXUS61 KPBZ 061735
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
135 PM EDT Sun Jul 6 2025

.SYNOPSIS...
Showers and storms return on Monday with a slow moving cold
front. Some of the rain may be heavy with localized flooding
possible. The boundary stalls Tuesday and an unsettled pattern
will bring daily rain chances throughout the week along with
near normal temperatures.

&&

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

- Major Heat Risk continues this afternoon for the Pittsburgh
  urban heat island.
- Dry conditions expected through tonight.
---------------------------------------------------------------

Temperatures have reached the mid to upper 80s early this
afternoon underneath a scattered summertime diurnal cu field.
Dewpoints have risen to the mid to upper 60s in many places,
resulting in heat indices climbing into the low 90s in some
spots already. Expect high temperatures to top out around or
just above 90 degrees over the next few hours, with heat indices
reaching the mid to upper 90s but remaining below Heat Advisory
criteria. The cu field should dissipate once again around
sunset with the loss of daytime heating, followed by another
quiet night with the warming trend continuing as lows remain in
the upper 60s to around 70 degrees. Some patchy fog and haze
will be possible again late tonight into early Monday morning as
moisture continues to advect back into the region and winds
remain light or calm.

&&

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

- Hot on Monday with heat indices in the upper 90s.
- Slow moving showers and storms Monday with a heavy rainfall
  and low-end severe weather threat.
- Boundary slows and stalls across northern WV maintaining daily
  precip chances.
----------------------------------------------------------------

An upper trough enters the region Monday and begins to flatten
out as it does so. Favorable timing of it will push Chantal`s
remnants to our east as Bermuda high pressure helps deflect it
to the north and east form the Carolinas. What we will see
locally is a weak cold front extending southward from a low
pressure system in Ontario slowly sweep through. Warm and moist
advection will continue ahead of the boundary and give the
region another chance to see high temperatures exceeding 90
degrees (60-90% south of I-80 but lower farther north owing to
increasing cloud coverage). Heat indices will creep up into the
upper 90s and some locales, especially urban areas and valleys,
may see 100. With increasing cloud cover/heavy rain arriving in
the afternoon, and the threat for advisory criteria very
localized, opted for no heat headlines in coordination with
neighbors.

The front will creep into our forecast area by the late
morning/early afternoon hours as convection fires along it aided by
daytime heating. Some showers may be ongoing in the morning across
northwest PA/eastern OH in weak pre-frontal convergence, but
not seeing more widespread development until later. The
environment will be supportive of heavy rain producers with
ensemble mean PWAT values >1.75", MUCAPE near 1500 J/kg, deep
warm cloud depths nearing 16,000 feet, and weak flow
characterized by MBE vectors around 10 knots oriented close to
boundary parallel. With the HREF in play, we have a better idea
of what sort of rainfall rates/amounts could be possible.
Probability for 1"/hour rates at any given hour tomorrow
afternoon and evening is as high as 60% and pegs the I-80
corridor. Even 2"/hour rates aren`t completely off the table
with some 10-20% blobs showing up. Total amounts through Monday
night exhibit a 40-70% probability of one inch, and a 15-30%
probability of two inches again with highest chances north of
Pittsburgh. With some time to recover since our last heavy rain
event, the area won`t be quite as hydrophobic, but soil
moistures are still elevated, so a flash flood risk is certainly
there and we remain in a Marginal Risk (1/4) for excessive
rainfall.

The other mention will be a low-end severe risk as a Marginal Risk
(1/5) clips our northern counties. With the aforementioned
destabilization, we`ll have the instability in play, but shear will
be weak overall (<20 knots deep layer). This points toward a water
loaded downburst threat given the PWATs, especially in any areas
that would see just a bit of mid-level drier air intrusion and nudge
up in DCAPE, which is possible to the north coincident with where
we`re outlooked for severe. A hail threat is nearly null given the
high moisture content and weak shear both detrimental to hail growth.

The boundary really struggles to move headed into the middle of the
week as mid-level flow parallels it. Latest ensemble clusters will
peg northern WV as the most likely spot for it to sit with solutions
coming into better agreement in the mid-levels. This is going to
provide us with daily, diurnally driven rain chances within the
proximity of the boundary as daytime heating fires showers and
storms off of it. A relief from the higher PWAT air seems unlikely,
so any of these showers and storms will be capable of locally heavy
rainfall. Southern and eastern portions of our region have been
included in a Tuesday Marginal Risk (1/4) for excessive rainfall.
The highest precip probabilities will remain mainly south of the
Mason Dixon line Tuesday along the front, though lower end
probabilities will exist farther north.

&&

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

- Stalled boundary plagues the area with daily precip chances
  through the end of the week
- Another system favored to move in over the weekend.
-------------------------------------------------------------------

A similar story for Wednesday keeping highest PoPs south of
Pittsburgh before low pressure tracking across the Great Lakes lifts
the boundary back up north as a warm front. This will overspread
higher precip chances to the area on Thursday and Friday as
additional waves of low pressure ride along the front. We should
finally rid our area of that disturbance just in time for another
one to develop out of the Northern Plains and bring yet another
unsettled pattern next weekend. Still some ensemble disagreement on
how that evolves, but not seeing too much confidence in a dry
weekend.

Temperatures are favored to hold just above normal through next
weekend, though with cloud cover and rain around, they may prove to
be slightly cooler than currently forecast in spots.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A scattered cu field with cigs around 5kft AGL has developed
across the area this afternoon, with generally light southwest
winds at all area terminals. A high confidence VFR forecast
remains in place through much of the current TAF period.
Increasing mid-level cloud cover and shower/thunderstorm
chances (and associated restriction potential) will work their
way back into the northwestern half of the forecast area towards
the tail end of the period as a cold front slowly approaches
from the northwest. Introduced PROB30s to reflect this timing at
ZZV and FKL, as well as in the extended portion of the PIT
30-hr TAF.

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
NEAR TERM...Cermak
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...Cermak