The remnants of Hurricane Ida impacted the mid-Atlantic on September 1, 2021. As it moved northward, Ida began transitioning to a strong mid-latitude cyclone with pronounced frontal features, but with continued tropical moisture. On a regional level, the remnants of Ida became one of the most severe natural disasters in US history, due to a combination of several tornadoes, some of them strong, as well as catastrophic flooding over a large and densely populated area. The severe weather threat unfolded as the system's developing warm front lifted northward from the Delmarva region into Pennsylvania and New Jersey. South of the warm front, partial clearing and moderate to strong instability developed. Meanwhile, very strong shear and forcing, along with tropical moisture, were present within the warm sector. The result was widespread convection in the form of both supercell and quasi-linear thunderstorms. A number of storms became severe across the region, producing several tornadoes and other instances of wind damage. This continued an exceptionally active stretch of high end severe weather in the region, coming barely a month after the tornado outbreak of July 29.

Tornado in BUCKS, PENNSYLVANIA
From 01-SEP-21 16:59:00 to 01-SEP-21 17:06:00 (EST-5)
Location: EDISON
Tornado F-scale: EF1
Crop damage: 0.00K
Reported by: NWS Storm Survey

The storm which produced a strong tornado in Montgomery County,
PA, cycled and produced another tornado in Bucks County, PA.
Damage began near in the area of Neshaminy Creek between Valley Rd
and Pebble Hill Rd in Doylestown. The tornado tracked north-
northeast from there, producing a consistent path of damage.
Damage was mainly confined to trees and was fairly extensive at
times, with much of the path length being heavily wooded. Numerous
hardwood and softwood trees were snapped and uprooted along the
path. Damage was strongly suggestive of tornadic winds, and a
tornado debris signature was also evident on radar. The heaviest
damage occurred near and along a stretch of Edison- Furlong Rd.
Extensive tree damage occurred along that road and a number of its
cross streets. Several utility poles were snapped in this area.
Tree damage along nearby Swamp Rd was also significant. The
tornado continued but began to lose intensity as it approached
Route 202, with sporadic tree damage observed on Mill Rd. Gradual
weakening continued and the tornado appeared to lift entirely in
the area of Burnt House Hill Rd. The extent of tree damage
suggested maximum winds of around 100 mph. No injuries were
reported as a result of this tornado.

Funnel Cloud in BUCKS, PENNSYLVANIA
From 01-SEP-21 18:09:00 to 01-SEP-21 18:09:00 (EST-5)
Location: EDGELY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A spotter in Florence reported a funnel cloud over the Delaware River.

Tornado in BUCKS, PENNSYLVANIA
From 01-SEP-21 17:30:00 to 01-SEP-21 17:35:00 (EST-5)
Location: BUCKMANVILLE
Tornado F-scale: EF1
Crop damage: 0.00K
Reported by: Public

A tornado embedded within a squall line developed several miles
southeast of the storm which produced a tornado in Buckingham
Township. Tornadic damage was first observed in the vicinity of
Stoneybrook Rd at Eagle Rd, near Jericho Creek. The tornado
tracked northeastward from there. It passed over the Jericho
National Golf Club, and sporadic tree damage mainly consisting of
uproots and large limbs snapped was observed in a path throughout
the golf course. It then moved over the adjacent Brownsburg Park,
where additional tree damage was observed and several soccer goals
were observed flipped in various directions. The tornado then
began to approach the Delaware River. Some minor tree damage was
observed along River Rd. However, the tornado appeared to lift
just slightly before reaching the Delaware River, with no apparent
damage on Pebbletown Rd just prior to the river. Throughout its
path, the tree damage produced by this tornado was fairly
sporadic, and it may have been discontinuous. Noticeable wind
damage was also observed for at least a mile east of the tornado
track, especially near its endpoint close to the Delaware River.
This is believed to be straight line wind damage, which is
corroborated by radar data, occurring around the rear flank
downdraft region of the tornadic circulation. However, the exact
length and width of the tornadic circulation is somewhat uncertain
due to the surrounding areas of straight line wind damage.

Tornado in BUCKS, PENNSYLVANIA
From 01-SEP-21 18:03:00 to 01-SEP-21 18:04:00 (EST-5)
Location: WEST BRISTOL
Tornado F-scale: EF1
Crop damage: 0.00K
Reported by: NWS Storm Survey

The tornado which began in Burlington County, New Jersey crossed the Burlington-Bristol Bridge and moved into Bucks County, Pennsylvania. As the tornado passed through a wooded floodplain along
the banks of the Delaware River, no visible damage was noted
either. The tornado then lifted just before reaching downtown
Bristol, PA, with several trees being snapped along the Bristol
Wharf.

Tornado in CHESTER, PENNSYLVANIA
From 01-SEP-21 15:15:00 to 01-SEP-21 15:22:00 (EST-5)
Location: OXFORD
Tornado F-scale: EF2
Property damage: 500.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An embedded supercell in a quasi-linear feature produced a
tornado near Oxford, PA. A path of damage began in crop land near
the intersection of 5th Street and Waterway Road. Tree damage
continued northeast of here.
Significant damage occurred in the Wiltshire Development. On Slate
Hill Drive, one house lost a southeast facing exterior wall.
Another house lost a significant amount of siding and a portion
of the roof. Tree damage continued in a northeast path. At Hickory
Hill Road, there was damage to the roof of a commercial
outbuilding and a recreational trailer was flipped on its side.
Sporadic tree and crop damage was noted from drone footage (this
portion of the path was inaccessible by vehicle) continuing to the
northeast. A metal storage building at a business along Reedville
Road had wall and roof damage. Further northeast there was damage
to turkey pens near the intersection of Baltimore Pike and West
Branch Road. Just a little further northeast, there was also heavy damage to a couple of barns, outbuildings, and porch structures on Conner Rd.
Additional tree and power pole damage continued in a northeast
path. The last damage noted along this continuous path was
exterior wall damage to a farm outbuilding and crop damage along
Street Road near Route 10. Sporadic tree damage was observed near
Route 10 and Ewing Road, but this does not appear to be in a
continuous path from the other damage, so this may have been
caused by straight line winds.

Tornado in MONTGOMERY, PENNSYLVANIA
From 01-SEP-21 16:35:00 to 01-SEP-21 16:49:00 (EST-5)
Location: FLOURTOWN
Tornado F-scale: EF2
Property damage: 5.00M
Crop damage: 0.00K
Reported by: NWS Storm Survey

A semi-discrete supercell thunderstorm began to exhibit rotation
over Delaware County, PA around 5:15 PM on September 1. The
rotation continued north-northeast into Montgomery County, and
eventually strengthened enough to produce a tornado. Minor tree
damage was first observed along Stenton Ave in Fort Washington in
the area of the Philadelphia Cricket Club. A path of tree damage
was observed heading northeast along Joshua Rd and through Fort
Washington State Park. Some minor shingle and siding damage to
houses was also seen.
Damage became more severe after the tornado crossed the
Pennsylvania Turnpike. At this time the tornado also moved into a
more residential area. Damage was observed along Montgomery Ave,
Spring Ave, and Prospect Ave and numerous crossing streets of
those. This mainly consisted of numerous snapped and uprooted
trees with minor to moderate roofing and siding damage to a number
of homes. The worst damage was observed slightly farther
northeast in the area of Stuart Creek in Upper Dublin. A number of
homes suffered partial to near total loss of roofing with many
damaged to the point of being uninhabitable. At least one home
experienced partial collapse of exterior walls consistent with EF2
tornado damage. Nearly all trees were snapped or heavily damaged
in this area as well.
Damage continued along Route 309 to the area of Upper Dublin High
School. The high school itself suffered roofing damage, and
significant roofing loss occurred to an Upper Dublin Township
building adjacent to the high school. A number of residences along
Loch Alsh Ave and several surrounding streets were also damaged.
A woman was killed when a tree fell on her home on Kenyon Dr, the
only known tornado-related fatality from this tornado or any
tornado during this regional outbreak.
Further northeast, damage occurred on and around the Temple
University Ambler Campus, again consisting of considerable tree
damage and partial roofing loss on a number of homes and
university buildings. The tornado then moved into Maple Glen,
crossing a heavily developed area near Norristown Rd at Limekiln
Pike. Snapped trees and mostly minor roofing and siding damage to
several commercial buildings was observed in this area. The
tornado remained continuous but did begin to lose some intensity
as it moved into Horsham Twp, traveling east of Limekiln Pike. A
number of trees were snapped along Babylon Rd. Near Horsham Rd,
roofing damage occurred to a veterinary hospital, along with
additional large trees snapped. Damage appeared to end not long
after that point. The tornado crossed Horsham Rd, but little to no
damage was observed in a couple of parks across the road,
approaching the Bucks County line. The tornado is believed to have
lifted in that area.