236
FXUS61 KPBZ 160142
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
942 PM EDT Tue Jul 15 2025

.SYNOPSIS...
Mostly dry today save south the WV ridges with heat risk
increasing. Daily severe and flood risk continue through at
least Friday, with a cooldown to near normal temperatures for
the weekend.

&&

.NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/...
KEY MESSAGES:

- Chance of afternoon storms in mostly WV high terrain; marginal
  risk of excessive rainfall for WV high terrain.
- Heat risk increases to moderate (with patchy major) today.
---------------------------------------------------------------

Evening Update...The unstable atmosphere still was able to
produce a few showers and thunderstorms this evening with little
storm motion. Updated the pops to account for this. This was the
only needed change. The convection should dissipate by 06Z.

Previous Discussion...A weak trough of low pressure exists on
the leeward side of the Appalachians, with both surface and
satellite imagery showing southeast flow for the day today. In
areas north of the surface front (including Pittsburgh), rain
and storm chances remain very low today with PWATS likely
hitting a early week minimum of 1.4" on the 12Z sounding. A
strong cap aloft with plentiful dry air above should limit
convective development north of I-70.

Elsewhere, in southeast flow, some high moisture from south of
the boundary will come streaming into the West Virginia ridges,
with some lift enhanced by orographics. The 12Z Sterling, VA
sounding showed this high moisture with PWATS of ~1.8" This will
lead to a chance of storm development. With minimal dry air in
the lowest 500mb on the sterling sounding, outflows and severe
potential looks generally unlikely, but this may also mean that
storms cold stall, tied to the high terrain ridge-top
convergence in the WV mountains. Conditional on storm
development and training, HREF maxima suggest the potential for
3" to 5" exists on a very localized bases, but this still
remains low probability.

Into the overnight hours, chances of rain drop off with loss of
heating and dews in the upper 60s to low 70s will inhibit much
cooling, keeping lows above normal and allowing patchy fog.

&&

.SHORT TERM /8 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
KEY MESSAGES:

- Wednesday and Thursday will feature an afternoon/evening
  chance of rain, heat, severe, and flooding, with flash
  flooding being the primary risk.

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

Any patchy fog will readily erode in the morning with mixing.
Through the day, a shortwave will cross the area, veering wind
profiles aloft and enhancing lift in the low levels. This will
translate to more warm, moist advection in the low-levels with
PWATS pushing back close to the 1.9" or 2" mark (between the
90th percentile and maximums). This southwest flow will also all
the northeastward push of the aforementioned front back across
the area as a warm front, allowing an additional defined forcing
axis.

This push in higher moisture air will also allow an increase in
the flow fields, with mean storm motions up to 15kts to 25kts.
With all the moisture in the profiles, severe chances appear
quite low unless the drier air aloft is slower to retreat or we
get deep morning convection (low probability). No dry air will
be favorable for flash flooding, however, with cold pools unable
to undercut showers and storms. Warm rain processes in the
lowest levels, long skinny CAPE (>95% chance of non-zero
MLCAPE), and potential for training, flash flooding risks
maximize tomorrow in the afternoon/evening hours. HREF maxima
tend to indicate as much as localized 3" to 5" of rain is
possible in eastern Ohio, with 2" to 4" of rain possible in PA
and WV.

After a decrease in convection, patchy fog in high moisture
overnight Thursday night, and lows above average yet again,
another active day is possible Thursday. Behind the shortwave
and the frontal passage, the area will be throughly warm
sectored Thursday with a bit more low-flow in wave of the
shortwave passage. This might slightly increase the chances of
severe, though PWATS appear to remain quite high near the 1.9"
to 2.0" PWAT range. Moisture be toward the lower end of the
distribution would be needed to realize any downburst wind
threats, otherwise, flash flooding remains the primary risk.
Warm overnight lows are expected again overnight with a decrease
in convective coverage. A weak cold front may enter the
northern fringes of the area overnight, cooling temperatures
for some along the I-80 corridor.

&&

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

- More seasonable conditions are likely Friday with
  precipitation chances mainly south of I-70.
- Any reprieve from storm potential is short-lived as active
  weather pattern likely resumes late Saturday into next week.
-------------------------------------------------------------------

The stalled surface cold front is likely to continue its
progression south through the morning. It`s expected to be
positioned south of Pittsburgh for most of the day Friday. For
areas north of the boundary, modest dry, cool advection and high
pressure will support dry weather and temperature close to or
even below seasonable average. For areas near to south of the
boundary, residual moisture and jet aided ascent is likely to
foster scattered afternoon thunderstorms; lowering PWATs and
weak shear should limit flood potential but keep the threat non-
zero.

Ensemble models favor a transient area of high pressure north of
the area to slide toward New England Saturday but provide enough
influence to promote mostly dry weather (though the linger
stalled boundary south of the area could spawn isolated
afternoon storms). This front will meander north and south
somewhere in the periphery of the area for most of the weekend,
dipping south and north on shortwave troughs/ridges. This
"front meandering" will continue to allow non- zero" rain,
severe, and and flooding chances through the weekend and early
next week though CIPS and ML keep chances respectively lower.
By the middle of next week, there is a bi-modal solution of
either developing weak eastern troughing or continued ridging.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
With the exception of a few showers and thunderstorms mainly
hanging near the ridge lines, the coming overnight should be
quiet after 02Z with the dissipation of the activity. Expect
VFR tonight with increasing high clouds ahead of an approaching
shortwave and surface warm front. This wave and warm front will
result in scattered showers by morning, with more numerous
showers and thunderstorm by noon and heading into the afternoon
with building diurnal instability.

Early convection during the late morning and into midday period
was handled with a PROB30 due to the spotty nature of the
convection with daytime heating on the rise. The period of time
with high confidence with maximum coverage will be 18Z through
00Z. Expect MVFR and IFR conditions around thunderstorms.

Outlook...Daily shower and thunderstorm chances are then
expected to continue, especially in the afternoons/evenings, as
the front becomes quasi- stationary and drifts across the
region. Fog and stratus is also possible each morning,
especially where rain fell the previous day.

&&

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

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...Milcarek/Shallenberger
SHORT TERM...Milcarek
LONG TERM...Frazier/Milcarek
AVIATION...WM/Shallenberger