030
FXUS61 KPBZ 160504
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
104 AM EDT Wed Sep 16 2026

.WHAT HAS CHANGED...
Update to Aviation Discussion.

&&

.KEY MESSAGES...
1) Shower and thunderstorm chances linger today and tomorrow
with a low risk of localized flooding and a non- zero chance of
severe weather.

2) Unsettled weather returns late Saturday into next week.

&&

.DISCUSSION...
KEY MESSAGE 1...
In line with the prior forecast update, this one maintains the
earlier arrival time of a cold front, sweeping down across the
area this afternoon and evening, before stalling tonight.
Provided that southwesterly surface flow through much of the
day will keep dew points >70F with 60% to 90% confidence and
temperatures climbing into the mid to upper 80s, the
thermodynamic setup will feel more like summer than fall. Ascent
aloft seems to be subtle during the day, which might hint to
convective chances being mostly tied to the front itself (north
of I-70), though warm and moist conditions with 500-1500 J/kg
SBCAPE (25th-75th percentile), and broad ascent mean pop up
storms could theoretically develop anywhere. Sfc-6km shear is
fairly weak, though most of this is packed into the sfc-2km
layer, meaning a spin up couldn`t be ruled out. That being said,
most of this is straight-line and westerly, so any rotation
would be dependent on a right moving (southeast moving) cell.
DCAPE will be more marginal, with 500-700 J/kg forecast, most
reliant on deep vertical development to realize gusty wind
potential. ML Outlooks are not very bullish at on on severe
potential, with both right movers and deep storms generally
unlikely, but the severe risk is non-zero nonetheless. What may
be more likely is localized flood in the event of any training
that might occur (particularly for urbanized corridors), with
PWATS pushing 1.8-2.0 inches (above the daily record) and warm
rainfall processes leading to efficient, heavy rainfall in and
storms that do develop.

00Z models have been more consistent with a second round of
storms developing upstream early Thursday morning, as a mid-
level shortwave accelerates low level flow above the nocturnal
inversion. Sfc-3km shear may increase to 20-30kts, with >90%
chance of non-zero MUCAPE with the 90th percentile as high as
1000 J/kg. Convective chances have increased, but timing still
remains uncertain. Most ensembles have these storms progressing
into the area around 6am Thursday, but outliers (NAM), show
development potential as early as midnight. Should this occur,
severe risk will be low with decoupling, but PWATS will remain
above record levels (1.9-2.1 inches), so localized flash flood
potential lingers for training storms or areas already hit from
the day prior. In the slowest scenarios for this passage, a very
low severe risk (weak spin up / winds) lingers for west PA /
north WV early Thursday should the atmosphere decouple late
morning. Coverage during the afternoon Thursday has trended down
behind this morning wave, but still non-zero storm chances
linger for the day (though severe and flood risks may be lower
than the prior update). Storm coverage Friday has also trended
lower with the only chance of rain/storms south of I-70 in the
event the front hasn`t fully cleared yet.


KEY MESSAGE 2...
A parade of shortwaves in WNW flow aloft allude to more chances
of rain and thunder by the weekend. Confidence remains highest
late Saturday into Monday (75% chance of rain). This will carry
more low-end severe/flood risks.

The pattern by the middle of next week remains uncertain, with
one camp of ensembles remaining unsettled and seasonable, in a
pattern similar to that of this weekend. Another camp bring a
cold front through, with cooler and drier conditions.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Confidence remains high in VFR through at least 22Z, outside of
the occurrence of any low probability (30%) showers/storms
tomorrow afternoon/evening. Storms are most likely to remain
widely scattered, but progress from northwest to southeast from
16Z to 02Z. These may bring brief vis/cig falls to MVFR.
Otherwise, light southerly breezes and low VFR cu decks are
expected into the day.

Overnight, MVFR cig decks may progress over the area but
coverage is likely to dependent on how may areas see rain
during the day. The current forecast follows a conservative
approach to drops to MVFR for FKL and DUJ (>50% likely).

Outlook...
Another wave passage is expected just outside of the TAF window
on Thursday morning, with more chances of showers and storms
with temporary cig drops. Convective coverage is likely to
remain scattered into Thursday afternoon/evening. Improvements
to VFR are likely Friday.

&&

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

&&

$$

DISCUSSION...Milcarek
AVIATION...Milcarek