Flash Flood Warning 100, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
317 AM EDT Tue Aug 11 2026

.WHAT HAS CHANGED...
The Flood Watch has been expanded northward to include
additionalcounties in eastern Ohio, northern West Virginia,
and far southwest Pennsylvania. Some models are hinting at a bit
more northerly track to the expected Tuesday night MCS, and
this trend will be monitored closely.

&&

.KEY MESSAGES...
1) Storms will bring near-daily flood and severe potential
through at least Wednesday.

&&

.DISCUSSION...
KEY MESSAGE 1...
Ongoing MCS will continue to cross the region and depart by
sunrise. Although some gusts to 40 MPH will continue to be
possible, the decrease of downdraft CAPE and the unfavorable
lapse rates have pretty much ended the severe threat for
tonight. Flash flooding threats will continue however, as pockets
of heavy rain can be expected in the 1.7 to 1.9 inch
precipitable water airmass, with training thunderstorms
producing localized bands of 2-3 inches of rain in an hour or
two. This threat should end by sunrise, with a lull in activity
in the subsidence behind the MCS.

Although scattered activity may develop this afternoon in the
destabilizing and still anomalously moist air mass, the main
concern is the next potent MCS that is forecast to begin to
organize over the Upper Midwest today and track southeast across
IN/OH and towards the Ohio River. While previous CAMs runs kept
this complex mostly off to our south and west, recent HRRR runs
are starting to trend towards a more northward track,
potentially impacting a larger portion of eastern Ohio, northern
West Virginia, and far southwest Pennsylvania around 00Z
Wednesday. However, HREF/REFS continue to keep the richer CAPE
to the southwest of CMH, with a gradient just to the southwest
of the CWA that may represent the previously favored track. The
current SPC outlook has a Slight (level 2 of 5) Risk for mainly
damaging wind gusts south of a PHD/HLG/MGW line. If current
HRRR trends continue and are supported by additional guidance,
this risk area may need to be nudged north with time, with
perhaps the introduction of an Enhanced (level 3 of 5) Risk to
in and around the ZZV area at least. If such an expansion
occurs, the chances of more significant wind gusts (into the
65-75 MPH range) would increase in the newly upgraded Enhanced
area.

Regarding future rainfall, HREF/NBM means have generally 1 to
1.5 inches in the area from around Pittsburgh to the south and
west through 12Z Wednesday. HREF maximums suggest 2 to 3 inch
stripes are possible in the region, with potential for more
storm training. The ongoing Flood Watch was extended northward
another row of counties, but still remaining south of Pittsburgh
at this time. Further northward expansion is possible later
today.

It must continue to be said that this entire forecast period
will remain low confidence, with each subsequent storm/threat
chance tied to the prior. Monitoring the forecast frequently
may be imperative. Wednesday and Thursday will bring additional
chances of severe and flash flooding, though chances of systems
slowly decrease through time as the development region is
expected to drift south into the central Appalachians.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Convective complex currently crossing the region is expected to
provide another 1 to 4 hours of rain and thunderstorms, with
occasional IFR visibility in downpours, and wind gusts of 20 to
30 knots in the heavier storms. Outside of thunderstorms, MVFR
to low VFR ceilings and lighter rain can be expected.

Conditions improve Tuesday morning and afternoon as ceilings
lift with the onset of heating/mixing. More shower and
thunderstorm activity is expected during the day Tuesday as this
unsettled weather pattern remains largely unchanged. Current TAF
forecasts reflect the most likely period of convection during
the late afternoon and evening hours, but overall confidence on
timing is fairly low at this time. Amendments will likely be
necessary.

Outlook... Active weather and associated restrictions continue
through much of the week with numerous rounds of showers and
thunderstorms. Unfortunately, confidence is low regarding the timing
of storms for any given day since it will depend heavily on how
convection evolves and progresses upstream during preceding
evenings/nights. Most restrictions during this period will be
tied to storm activity and/or morning fog and stratus due to moisture
remaining trapped near the surface.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch through Wednesday morning for PAZ031.
OH...Flood Watch through Wednesday morning for OHZ039-048-049-
     057>059-068-069.
WV...Flood Watch through Wednesday morning for WVZ003-004-012-021-
     509>514.

&&

DISCUSSION...CL/Milcarek
AVIATION...CL/Cermak

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Preliminary Local Storm Report
National Weather Service Pittsburgh PA
347 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1039 AM     Tstm Wnd Dmg     3 SW Hanoverton         40.72N 80.98W
08/10/2026                   Carroll            OH   Public

            Report of State Route 9 closed at Marble
            Road due to downed tree over roadway. Time
            estimated based on radar.

&&

JF

Preliminary Local Storm Report
National Weather Service Pittsburgh PA
407 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0323 AM     Flash Flood      6 NNE Markleysburg      39.81N 79.40W
08/11/2026                   Fayette            PA   911 Call Center

            MAE WEST RD WILL BE SHUT DOWN NEAR SUGAR
            LOAF RD AT THE BASE BY ELECTION HOUSE HILL.
            ROAD IS WASHED OUT AND LARGE SECTION OF ROAD
            IS COLLAPSED. Time based on report.

&&

Lupo

Preliminary Local Storm Report
National Weather Service Pittsburgh PA
448 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0448 AM     Flash Flood      Hanoverton              40.76N 80.94W
08/11/2026                   Columbiana         OH   Dept of Highways

            Report of State Route 9 closed in both
            directions due to flooding.

&&

JF

Preliminary Local Storm Report
National Weather Service Pittsburgh PA
449 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0449 AM     Flash Flood      4 NE Hanoverton         40.79N 80.89W
08/11/2026                   Columbiana         OH   Dept of Highways

            Report of State Route 172 closed in both
            directions at Hanna Drive due to flooding.

&&

JF

Preliminary Local Storm Report
National Weather Service Pittsburgh PA
518 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0415 AM     Flash Flood      5 NNE Markleysburg      39.80N 79.40W
08/11/2026                   Fayette            PA   911 Call Center

            Report of State Route 281, Mae West Road,
            closed in the 1000 block due to road being
            washing away or collapsed with heavy rain.
            Time estimated based on radar.

&&

JF

Preliminary Local Storm Report
National Weather Service Pittsburgh PA
617 AM EDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 AM     Flash Flood      4 NE Markleysburg       39.78N 79.41W
08/11/2026                   Fayette            PA   Public

            Report of Tub Run Road flooded and
            impassable. Time estimated based on radar.

&&

JF