756
FXUS61 KPBZ 140101
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
901 PM EDT Fri Jun 13 2025

.SYNOPSIS...
Near-normal temperatures continue through early next week with
occasional storm and flash flooding chances. Heat may return by
mid-week.

&&

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

- Shower and storm coverage increases this afternoon with a
  marginal risk for flash flooding.
---------------------------------------------------------------

A bit of convergence in the low levels along a stalled boundary
may allow enough surface convergence for storms to initiate
today, most likely in the 2pm to 8pm timeframe. Moisture
advection allowed up to 1.43 PWATS to enter the area with flow
generally less than 20kts below 600mb. This is approaching the
90th percentile of PWAT climatology; combined with weak flow
this will allow for a marginal flash flooding threat into the
afternoon and evening as convective coverage increases with a
bit more instability generation. The exact location will be
difficult to wash out with a fairly homogeneous environment,
but CAM probabilities are a bit higher around and north of
Pittsburgh along a surface convergence boundary with perhaps
higher chances in the ridges in orographics. HREF max 1hr
precipitation totals are around 1 to 1.5 inches, right around
1hr flash flood guidance, but training certainly increases
flooding threat should it occur if convection fires on outflow.
Severe threats remain very low. The 12Z DCAPE was about 600, but
upstream observations indicate more moisture and less DCAPE is
on the way (as evidenced by 400 DCAPE on the Wilmington, Ohio
sounding).

Chances decrease overnight with the loss of the surface based
component of instability, though a weak mid-level wave that
encroaches late tonight may allow additional shower and low-
probability storm chances through the late-night and early
morning hours, though flood risks may be a bit lower. Bountiful
moisture and cloud cover may keep lows 5 to 10 degrees above
average.

&&

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

- Continued storm chances with flash flooding threats Saturday.
----------------------------------------------------------------

Surface convergence up along the stationary boundary will
continue as the aforementioned mid-level wave moves up to and
north of Pittsburgh, allowing for rain chances with perhaps a
rumble of thunder tomorrow morning. While HREF maximum rain
rates tend to show a bit lower with this round, approximately
0.5 to 1 in/hr with slightly less instability, coverage may be a
bit more widespread, PWATS will be slightly higher, and there
is at least some training potential along the boundary. This
will support a marginal threat of excessive rainfall
conditional on training.

How this morning round shapes up may affect how an afternoon
round of storms sets up. Cloud cover and morning rain may keep
temperatures a tad bit cooler and the environment more stable to
the north, but south of Pittsburgh, the airmass may be
uncontaminated with perhaps a fractionally lower low cloud
fraction. This might be more supportive of thunderstorms with
higher rain rates in near-clamatologically maximum PWAT air in
the afternoon (1.65 to 1.75). With better surface heating in
this environment, one might expect flash flooding potential
unconditional of training yet again in the afternoon with and
more intense updrafts in efficient warm rain processes through
a deep, saturated column in weak flow. Some CAMs hint at the
highest storm coverage along the east-west axis intersecting
Pittsburgh on a modest thermal gradient. While coverage and
intensity may decrease after sunset, flash flooding could not
be ruled out in training yet again.

All in all, cloud cover, rain chances, and deep saturation
should keep daytime highs slightly cooler than Friday, and lows
around 5 to 10 degrees above average yet again.

&&

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

- Rain and flooding chances linger through early next week,
  before a mid-week warmup.
-------------------------------------------------------------------

By Sunday, the mid-level disturbance and corresponding surface
low will approach the upper Ohio Valley, along for a continued
saturated environment (with PWATS near the 90th percentile),
warm rain processes, and mostly-diurnal storm chances in weak
flow. This will maintain marginal flash flooding threats with
chances peaking in the afternoons and subsiding overnight. There
is some indication the main surface convergence will be focused
around and southeast of Pittsburgh as the low very slowly pulls
off the coast. Monday chances will depend more the trough
departure timing. Should the trough pull off faster (American,
Euro ensembles; 65% of membership), flooding chances will be
lower. Should the trough be slower (Canadian ensembles; 35% of
membership), flood chances may linger.

By Tuesday and Wednesday, there is some indication of a return
to quasi-zonal flow to even weak ridging, with 80% membership in
clustering suggesting heights between 583dm and 586dm and NBM
highs back into the mid to upper 80s. Beyond that, into late
week, there is some indication of troughing with both timing and
intensity uncertainty. This keeps Friday high temperature
spread anywhere between the mid 80s and upper 70s.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
While evening coverage of convection is increasing, the
potential for deeper updrafts capable of ice production and
growth remains quite low, given weak lapse rates aloft.
Therefore, potential for prolonged and vigorous tsra is low at
all terminals overnight.

Models remain committed to broad coverage of showers
consolidating in a band of moderate to locally heavy rain along
the I-80 corridor late tonight into Sat morning before this band
shifts ewd. Impacts from this band are likely at least at
DUJ/FKL, where vsby could be reduced below 2SM at times, but is
likely to oscillate between IFR and MVFR. There is greater
confidence (70-100% chance) in sustained IFR ceilings, however,
at most terminals in PA late tonight thru mid-morning, with a
period of time where ceilings fall below 1kft.

By late morning, ceilings at most terminals (except DUJ/FKL)
are likely to lift to MVFR as breaks of sun facilitate deeper
mixing. But lacking a thermal cap, even modest heating should be
sufficient to invigorate more robust updrafts by early
afternoon, with tstms possible for a few hours at almost all
terminals south of I-80. Although prevailing conditions will
favor MVFR during this time, drastic drops in vsby are
possible(30-40% probability) within the very heavy rain of
afternoon storms.

Outlook...
Restriction potential with rain will continue into early next
week with little change in pattern as a series of disturbances
crosses the area.

&&

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

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...Kramar