237
FXUS61 KPBZ 151846
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
246 PM EDT Sun Jun 15 2025

.SYNOPSIS...
Near-normal temperatures continue through early next week with
periodic shower and storm chances. Localized flooding will be
possible. Daytime highs return to above normal by the middle of
next week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:

- Scattered showers and thunderstorms continue, mainly PGH and
  to the south
- Locally heavy rain may result in flash flooding
---------------------------------------------------------------

There are minimal environmental changes today as a stationary
boundary remains over eastern OH through west central PA,
promoting heavy rain showers and isolated thunderstorms mainly
south of I-80. The factors supporting the Flood Watch for
southwest PA, eastern OH, and northern WV (and non- zero chances
outside):

- PWATs above the 90th percentile that approach daily maximum,
  indicating a moisture-rich environment
- Deep warm cloud depth sounding (12z sounding shows moisture
  through 13kft)
- Slow storm motion with Corfidi vectors around 3kts
- Lift sources from a stationary surface boundary plus an
  approaching weak PVA that could aid deformation zones
- Buoyancy near 1000J/kg

Showers will generally be light through the morning hours as
buoyancy remains limited, but become heavier between noon to 8pm
as the various factors above are maximized. HREF probabilities
for greater than 1" totals over 3 hours remains highest in the
watch area, but storm-scale processes (like outflow collisions)
are likely to play greatest role in the locations that may see
flooding and difficult to pinpoint ahead of time.

Loss of diurnal heating is likely to reduce storm coverage and
flooding risks at 8pm, but rain could persist based on residual
storm outflow collisions. Overnight patchy fog may again develop
in the region as the boundary layer remains moisture rich and
flow is light.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Slight Risk Outlook for Excessive Rainfall
- Similar flash flood chances Monday & Tuesday, mainly south of
  Pittsburgh.
----------------------------------------------------------------

Rain from this weekend has saturated the soil in many locations
such as Venango County (PA) and Ohio County (WV). These
antecedent conditions make these areas more vulnerable to flash
flooding. With a weak, stationary trough, high moisture is expected to
persist.

On Monday, precipitable water above the 90th percentile,
surface CAPE up to 500 J/kg, and weak flow combine to provide a
favorable environment for diurnal shower and storm chances.
Similar to Saturday and Sunday, any storms that pop-up could
remain relatively stationary and produce higher rain
accumulations in an hour. This risk will remain in areas south
of Pittsburgh where there is a Slight Risk for excessive
rainfall. Timing is expected mainly between noon and 8pm.

The chance for showers will persist overnight, however, without
the daytime heating, they will likely be lighter. A similar
environment is expected to set-up on Tuesday keeping the chance
for flash flooding in play with a Slight Risk Outlook for
excessive rainfall. Rainfall is expected to lighten Tuesday
night into Wednesday.

&&

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

- A mid-week warmup will be followed by increasing late-week  severe
potential.
- Weekend is likely to be dry and hot.
-------------------------------------------------------------------

By Wednesday, there is some indication of a return to quasi-zonal
flow to even weak ridging, with NBM highs back into the mid to upper
80s. On Thursday, a surface low (preceding an upper level
trough), is expected to move through the area bringing the
chance for severe weather. We will be keeping an eye on severe
potential in the transition from heat to weak troughing, with
CIPS and CSU machine learning showing increasing probabilities
into Thursday and Friday. Into days 7 and beyond, the strength
and progressiveness of this trough will determine just how long
it takes to warm back up into what could potentially be another
ridging pattern with heat returning.

By Saturday, a ridge is likely to move into the area, bringing dry
weather and warm temperatures. Temperatures are expected to rise
into the mid to upper 80s. The ridge is expected to remain
stationary at least through Monday keeping temperatures well above
normal into the upper 80s and low 90s

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
A stationary boundary and approaching weak PVA will create
scattered to numerous showers with isolated thunderstorms south
of I-80 through 00z before diurnal heating loss reduces storm
coverage/intensity. Morning restrictions will lift as mixing
commences while the environment generally favors VFR by 18z but
MVFR to locally IFR within rain showers. Rainfall rates in the
stronger storms could exceed 2" but gusty wind potential remains
low.

The stagnant, moist environment is likely to remain fairly
unchanged overnight and allow for restriction deterioration
toward MVFR/IFR conditions and patchy fog.

Outlook...
Periodic restrictions are expected through Thursday as
disturbances track along the stalled frontal boundary across the
Upper Ohio Valley region. Late night/early morning stratus and
fog is likely, along with showers and thunderstorms peaking in
the afternoon and early evening. More organized showers/storms
are expected with a Thursday cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch until 8 PM EDT this evening for PAZ021-029-031-
     073>076.
OH...Flood Watch until 8 PM EDT this evening for OHZ049-050-058-059-
     068-069.
WV...Flood Watch until 8 PM EDT this evening for WVZ001>004-012-021-
     509>514.

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...Frazier
SHORT TERM...Lupo
LONG TERM...Milcarek/Lupo
AVIATION...Frazier