933
FXUS61 KPBZ 171131
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
731 AM EDT Thu Sep 17 2026

.WHAT HAS CHANGED...
The flood threat for today seems to be more isolated. Updated
for the 12z TAF issuance.

&&

.KEY MESSAGES...
1)Thursday offer risks for flash flooding alongside a nominal
wind threat.

2) Unsettled weather returns late Saturday into next week.

&&

.DISCUSSION...
KEY MESSAGE 1...
A 500MB minor shortwave trough is expected to cross the area
today as the cold front that has been draped from west to east
across the area. Still a slight west-northwest flow is expected
through the day. This is expected to push the cold front through
the area by 00Z tonight. Ahead of the front, additional shower
and thunderstorm activity is expected to develop today. A still
rather moist environment is in place.

PWATs are expected to be 1.8 to 2.0 through the day today and
some spots could be up to 2.1 PWATs, giving an idea how much
moisture is in the atmosphere for today. NBM probabilities tend
to be a bit low on the rainfall expectations but the HREF gave a
24 hour rainfall prob of exceeding 0.50" at around 30% to 50%.
Thus, despite the saturated atmosphere, the moisture seems to
be under utilized. Still some 1000 to 1500 SB CAPE is possible
today and enough to expect some instances of thunderstorms with
enough instability to work with, to produce some heavy rainfall.
The bulk of the instability being mainly in southeast Ohio.
Thus, expect at least some isolated instances of flooding and a
non-zero chance for a strong storm or two.

KEY MESSAGE 2...
Surface high pressure within brief NW flow supports at least 1
day of dry weather as temperature drops below the 80s (but
remains above normal). But the longwave pattern is favored by
ensemble models to position upper ridging over the Tennessee to
lower Mississippi River Valleys while driving a series of
shortwaves over the ridge top through the Ohio River Valley. The
result is more waves of showers and thunderstorms through early
next week that, pending the localized storm environment for a
given day, could contain various hazard threats.

The most likely hazardous risk over this time frame is flash
flood given guidance maintains mean PWAT values between 1.4" to
1.9" inches (between the 90th to above daily max, respectively).
This risk could be further exacerbated if the region does
experience multiple rounds of heavy rain (even starting
tonight/Thursday) that causes near-saturated grounds that
significantly lowers flash flood guidance. It may be
meteorological fall, but summer-like storm risks bear monitoring
into early next week.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Showers, thunderstorms and fog begin the period. With more
active instances of rain, LIFR fog is expected to break up some
here, although mist can continue for the next several hours
before slowly dissipating in the mid-morning hours. Continued
IFR restrictions in heavy downpours can accompany any showers or
storms across the region but progressively longer periods of
dry conditions are expected between these as we move towards
midday and the afternoon. Bouts of MVFR CIGs are expected to
slowly lift through the morning as we begin to mix into VFR CIGs
by this afternoon.

Models continue to point at the redevelopment of thunderstorms
across the area by early afternoon but confidence in timing and
area remain very low at this time. As such PROB30s remain and
will be massaged over the course of the morning to reflect
evolving conditions. The highest confidence in storm occurrence
is likely later this afternoon near and south of I-70 for ports
like ZZV, HLG and MGW.

Winds are expected to be light and variable through much of the
day and then shift out of the west up to 10 knots at times.
Winds will be gusty within thunderstorms during the afternoon.
Convection is expected to wane and dissipate in the 00Z to 06Z
period. Fog is possible again tomorrow morning, and becomes
more likely across areas that see heavy rain today.

Outlook...
Improvement to VFR is likely Friday under high pressure.
Saturday night, restrictions are likely to return with an
increase chance for showers and thunderstorms associated with
an approaching disturbance.

&&

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

&&

$$

DISCUSSION...Frazier/Shallenberger
AVIATION...Shallenberger/AK