784
FXUS61 KPBZ 160049
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
849 PM EDT Sat Aug 15 2026

.WHAT HAS CHANGED...
A Flood Watch has been issued for counties near and south of
Pittsburgh from 04Z Sunday to 12Z Monday, as confidence has
increased in potentially flooding rain. There is also slightly
higher confidence in the potential for severe storms mainly
south of I-70 Sunday afternoon and evening. Updated for the 00z
TAF issuance.

&&

.KEY MESSAGES...
1) Overnight cluster of storms will bring heavy rainfall and
flood potential to eastern Ohio, northern West Virginia and
possibly southwestern Pennsylvania.

2) Sunday storm evolution is lower confidence as it depends on
the evolution of overnight storms, but flash flood and severe
risks remain possible Sunday afternoon with potential renewed
storms.

3) After lingering showers dissipate Monday, there is fairly
high confidence in dry weather until Wednesday/Thursday, when
low pressure returns.

&&

.DISCUSSION...
KEY MESSAGE 1...
Storms are beginning in western/central Ohio associated with
approaching low pressure. CAMs have latched onto the storm
development, but continue to struggle with the system`s
movement, with 18Z runs suggesting more of an ewd trajectory
after 12Z runs` sewd movement.

Regardless of the system movement, the environment remains
primed for heavy rainfall, with 00Z RAOB indicating PWAT value
just under 2.00" and modest low-level buoyancy almost wholly
beneath the freezing level. Any initial low-topped showers will
heavily feature warm-rain processes, efficient rainfall and very
little lightning.

One or more localized axes of 1.5-2.5" rain seems possible
overnight somewhere from PHD/ZZV-HLG-MGW, but where these axes
of heaviest rainfall eventually materialize still remains
uncertain. Wherever they occur, however, flash flooding will be
possible given prior wet ground, and heightened awareness is
warranted given the unusual time of day for flash flooding.

With continued deep moisture advection into the region, PWAT
could climb as high as 2.20-2.25". If the 12Z sounding records
PWAT values in that range, it would be one of the highest such
readings ever recorded at KPIT (since 1952). Regardless, PWAT
values are anomalously high, and a prolonged period of potential
heavy rainfall from multiple rounds of storms remains in the
offing. The Flood Watch will continue until Monday morning.

KEY MESSAGE 2...
Confidence in what follows for Sun and Sun night drops off, as
atmospheric recovery/Sun-afternoon storm evolution will depend
on the mesoscale setup left behind by the overnight complex.
While stable morning air should limit coverage and intensity of
convection at least into early afternoon, redevelopment appears
increasingly likely tied to a potential mesoscale convective
vortex developing from storms in the Midwest/northern Plains.

Here, a pocket of 25-30 knots of 0-6km shear could provide
enough storm organization for a damaging wind potential, while
elongated/curved low-level hodographs (particularly enhanced by
a MCV if present) and sufficient 0-1km SRH suggest a lower-end
tornado threat for esewd-moving storms. Machine-learning
guidance does support these assertions, likely picking up on
MCV-enhanced fields. Also, the same favorable heavy-rainfall
ingredients from the previous night will continue, extending the
flash flood threat into Sun night.

KEY MESSAGE 3...
Diurnal stabilization should begin to limit convective coverage
and intensity late Sun evening, with a few showers lingering
into Mon with one last shortwave trough. By this point, PWAT
will be dropping off thanks to developing drier nwly flow,
which should help to taper the heavy-rainfall threat. High
pressure building in from the Great Lakes should end
precipitation by Mon evening. Dry weather is then favored until
Wed, when the next front could potentially arrive, although
this timing could change.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR is expected through this evening under shortwave ridging,
though scattered cumulus and increasing mid level clouds are
expected ahead of an approaching shortwave trough. A warm front
will approach and cross the region tonight into Sunday morning,
with showers, embedded thunderstorms, and MVFR to IFR
restrictions expected. Elevated instability and a low level jet
should maintain storms overnight into Sunday morning. ZZV and
MGW have a higher potential of seeing thunderstorms tonight, so
included a tempo mention for thunder there. Maintained a prob30
for most other airports with a somewhat lower chance of thunder.

IFR restrictions are expected Sunday morning with additional
showers/embedded thunderstorms as the warm front moves northeast
across the area. Afternoon thunderstorms are likely on Sunday
as a cold front approaches, mainly after 18Z. Included a tempo
mention in the 30hr PIT taf beginning at 20Z.

Outlook...
A few showers and restrictions could continue Monday as the
cold front completes its passage. General VFR is then expected
through Tuesday under high pressure. Restrictions and
shower/thunderstorm chances return later Wednesday into early
Thursday with the approach and passage of another cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from midnight EDT tonight through Monday morning
     for PAZ020-021-029-031-073>076.
OH...Flood Watch from midnight EDT tonight through Monday morning
     for OHZ039>041-048>050-057>059-068-069.
WV...Flood Watch from midnight EDT tonight through Monday morning
     for WVZ001>004-012-021-509>514.

&&

$$

DISCUSSION...Kramar/CL
AVIATION...WM/AK