939
FXUS61 KPBZ 141752
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
152 PM EDT Sat Jun 14 2025

.SYNOPSIS...
A flash flood watch is in effect portions of Pennsylvania
through the evening. Near- normal temperatures continue early
week with occasional daily flash flood and precipitation
chances. Temperatures warm up towards the middle of next week.

&&

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

- Convection has started to bubble on an axis across the middle
  of the forecast area, which will carry the brunt of flooding
  threats into tonight.
---------------------------------------------------------------

PWATS will be slightly higher this afternoon (on the order of
1.7" to 1.8" (1.78" on the 12Z sounding) or >90th percentile of
climatology. Satellite into the afternoon shows evidence of
clearing in all areas save northwest PA, that will allow a
favorable environment for instability generation and
convection. 2pm trends show the development of towering cu and
cb reflecting this, as an uptick in rainfall rates is expected
over the next couple of hours. With better surface heating in
this environment, one might expect flash flooding potential. The
highest threat will be along the east-west outflow dropping
south from Butler across the center of the forecast area near
Pittsburgh, particularly areas where the flow and boundary
orientation are parallel in an east-west direction with
training. This is mostly in the southern half of the flood
watch.

In other areas, particularly south of the boundary, flash
flooding is also possible but the ability to generate training
convection will be harder with no established boundary.
Nonetheless, discrete cells over an area for long enough will be
able to generate flood threats with a deep warm rain layer and
near record PWATs in weak flow.

After collaboration with WPC, this will justify a slight risk
for excessive rainfall over portions of western PA in the
afternoon and evening hours. 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.

&&

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

- Continued storm chances with flash flooding potential continue
  Sunday and Monday.
----------------------------------------------------------------

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. WPC has increased the flood risk some, particularly for
northern West Virginia (slight risk of excessive rainfall) in
the area where there is currently the highest confidence in the
best moisture and forcing as the low drags east and storm
motion may be a bit slower on the northern fringes of the weak
low. HREF max 1hr precipitation rates are the highest we have
seen seen thus far, up to 2" to 3" an hour in very localized
spots. This threat maximizes between 12pm and 8pm.

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, more confined to northern West Virginia
again on the northwest side of the low.

&&

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

- A mid-week warmup will be followed by increasing late-week
  severe potential.
-------------------------------------------------------------------

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, there is increased
confidence similar heat lingers into at least Thursday at this
point with most ensemble spread encompassed in the 80s.

Beyond that, into Friday and beyond, there is some indication
of troughing with both timing and intensity uncertainty. Though,
in the last 24 hours this has trended slower and weaker,
keeping much of the late week temperature spread in the low to
mid 80s, providing some, but not dramatic relief. We will also
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.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Most of the area has improved to MVFR prevailing ceilings and
visibilities this afternoon, with the exception being FKL/DUJ
where IFR/LIFR lingers as showers from this morning are still
working on exiting that area. Satellite sensors have detected a
few flashes of lightning in some of the taller convective cells
that have formed along a boundary currently draped from New
Philadelphia, OH to Dubois, PA. This boundary will sag southward
through the remainder of the afternoon, bringing showers and
occasional rumbles of thunder to PIT/AGC/LBE over the next few
hours. Some widely scattered convection is also beginning to
percolate south of the boundary where brief instances of rain
and thunder could impact HLG/MGW through mid afternoon.

Convection will wane around sunset with the loss of daytime
heating, though a few isolated showers may linger into early
overnight hours mainly south of PIT. Widespread IFR/LIFR
ceilings and visibilities return overnight into early Sunday
morning given a very saturated near-surface layer. Gradual
improvement back to MVFR occurs mid to late Sunday morning along
with an uptick in shower and thunderstorm chances as daytime
heating promotes deeper mixing and convective initiation.

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...Flood Watch until 8 PM EDT this evening for PAZ008-009-014>016-
     022-077-078.
OH...None.
WV...None.

&&

$$

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