A low amplitude, positively-tilted shortwave trough crossed the eastern Great Lakes/upper Ohio Valley region on October 2nd.  Showers and thunderstorms developed in a moist, unstable air mass across eastern Ohio, northwestern Pennsylvania, and northern West Virginia. Despite expansive early morning cloud cover, some clearing was observed, allowing for a substantial buildup of instability, while dewpoints in the mid to upper 60s illustrated the available moisture.  The crossing shortwave and associated mid-level jet resulted in 40 knots of deep layer shear and a wind profile which favored discrete cells. As a result, several supercells and tornadic signatures were observed.
A total of six tornadoes were observed in the Pittsburgh forecast area, with ratings ranging from EF-0 to EF-2.  The most significant damage was observed with a tornado that resulted in damage to homes and gravestones in the vicinity of Jefferson Cemetery in Jefferson County.  No deaths or injuries were reported from these tornadoes. Several reports of hail up to golf ball size were also received, as well as reports of straight-line wind damage.
In all, 14 tornadoes occurred in the state of Pennsylvania on this day.  The previous record number (since 1950) of tornadoes on an October day was four on October 5, 1979.  Overall, there are only three days with more Pennsylvania tornadoes recorded:  May 31st to early June 1st, 1998 (23 tornadoes), June 2nd, 1998 (22), and May 31st, 1985 (21).

Hail in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 17:00:00 to 02-OCT-18 17:00:00 (EST-5)
Location: RED MILL
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in GREENE, PENNSYLVANIA
From 02-OCT-18 17:12:00 to 02-OCT-18 17:12:00 (EST-5)
Location: CARMICHAELS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 17:38:00 to 02-OCT-18 17:38:00 (EST-5)
Location: BROCKWAY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in FOREST, PENNSYLVANIA
From 02-OCT-18 16:10:00 to 02-OCT-18 16:10:00 (EST-5)
Location: BYROMTOWN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in FOREST, PENNSYLVANIA
From 02-OCT-18 16:13:00 to 02-OCT-18 16:13:00 (EST-5)
Location: BYROMTOWN
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:30:00 to 02-OCT-18 16:30:00 (EST-5)
Location: HUNKER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:37:00 to 02-OCT-18 16:37:00 (EST-5)
Location: CARBON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 15:59:00 to 02-OCT-18 15:59:00 (EST-5)
Location: PLEASANT VLY
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported a tree and wires down along Paintertown Road, blocking the roadway.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:05:00 to 02-OCT-18 16:05:00 (EST-5)
Location: BROOKVILLE
Magnitude: 50.00 EG
Property damage: 1.50K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported multiple trees and power lines were blown down along State Route 28.

Thunderstorm Wind in FOREST, PENNSYLVANIA
From 02-OCT-18 16:10:00 to 02-OCT-18 16:10:00 (EST-5)
Location: BYROMTOWN
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported that large limbs were blown down along Watson Farm Road.

Thunderstorm Wind in GREENE, PENNSYLVANIA
From 02-OCT-18 16:21:00 to 02-OCT-18 16:21:00 (EST-5)
Location: GRAYSVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

County law enforcement reported that trees and power lines were blown down in town.

Thunderstorm Wind in GREENE, PENNSYLVANIA
From 02-OCT-18 16:23:00 to 02-OCT-18 16:23:00 (EST-5)
Location: GRAYSVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

County law enforcement reported that trees and power lines were blown down along Stringtown Road.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:31:00 to 02-OCT-18 16:31:00 (EST-5)
Location: RED MILL
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that multiple trees were blown down near Falls Creek.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:31:00 to 02-OCT-18 16:31:00 (EST-5)
Location: NEW STANTON
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

According to county 911 officials, a tree and wires were blown down, blocking 7th Street.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:31:00 to 02-OCT-18 16:31:00 (EST-5)
Location: YOUNDWOOD
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that multiple trees were blown down, blocking Waycross Road.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:34:00 to 02-OCT-18 16:34:00 (EST-5)
Location: RED MILL
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported uprooted trees at the intersection of 4th Street and Osborne Avenue.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:34:00 to 02-OCT-18 16:34:00 (EST-5)
Location: BAXTER
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported minor roof damage to a house along State Route 28.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:34:00 to 02-OCT-18 16:34:00 (EST-5)
Location: ARMBRUST
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported multiple trees down along Stone Church Hill Road in Hempfield Township.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:34:00 to 02-OCT-18 16:34:00 (EST-5)
Location: HUNKER
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported multiple trees down in New Stanton.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:37:00 to 02-OCT-18 16:37:00 (EST-5)
Location: BAXTER
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that multiple trees were blown down on Weaver Road.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:37:00 to 02-OCT-18 16:37:00 (EST-5)
Location: ARMBRUST
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that multiple trees were uprooted with sheared tops.

Thunderstorm Wind in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:38:00 to 02-OCT-18 16:38:00 (EST-5)
Location: ARMBRUST
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A storm survey found that a number of trees were felled in a copse along Stone Church Hill Road, which appears to be associated with wind in the forward flank downdraft of the tornadic thunderstorm.

Thunderstorm Wind in GREENE, PENNSYLVANIA
From 02-OCT-18 16:39:00 to 02-OCT-18 16:39:00 (EST-5)
Location: SYCAMORE
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that trees were blown down on  WW Railroad Road.

Thunderstorm Wind in GREENE, PENNSYLVANIA
From 02-OCT-18 16:58:00 to 02-OCT-18 16:58:00 (EST-5)
Location: KHEDIVE
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that trees and wires were blown down along Ridge Road.

Hail in FOREST, PENNSYLVANIA
From 02-OCT-18 16:13:00 to 02-OCT-18 16:13:00 (EST-5)
Location: BYROMTOWN
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 02-OCT-18 15:20:00 to 02-OCT-18 16:20:00 (EST-5)
Location: ROOK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported roadway flooding in the 1000 block of Washington Avenue in Scott Township.

Tornado in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:03:00 to 02-OCT-18 16:13:00 (EST-5)
Location: ROSEVILLE
Tornado F-scale: EF0
Reported by: NWS Storm Survey

Eyewitness accounts and several videos confirm that a tornado
initially touched down just west of the Moonlight Drive-In Theatre
along US322 just west of Brookville. Sporadic minor to moderate
tree damage was observed along a 4 mile track to the east, last
observed along Kirkman Rd just north of the 82 mile marker of
Interstate 80. The track is presumed to have crossed Interstate 80
roughly at the North Fork Creek bridge.

Tornado in GREENE, PENNSYLVANIA
From 02-OCT-18 16:26:00 to 02-OCT-18 16:28:00 (EST-5)
Location: GRAYSVILLE
Tornado F-scale: EF1
Reported by: NWS Storm Survey

Visible tree damage began along a hilltop near Martin Rd, but
became concentrated in the valley along Stringtown Road northeast
of Graysville PA, where numerous hardwood and softwood trees were
snapped or uprooted. A home in this location lost its deck roof
and fascia.
Several outbuildings were destroyed, including a shed that was
found mangled upwind from its prior location, and an open metal
canopy that was removed, mangled and deposited in a field
downstream. Another outbuilding exhibited metal roof panel
peeling.
The damage continued sporadically until Grange Road, where
threshold tree damage was noted.

Tornado in JEFFERSON, PENNSYLVANIA
From 02-OCT-18 16:33:00 to 02-OCT-18 16:41:00 (EST-5)
Location: HARLAN
Tornado F-scale: EF2
Reported by: NWS Storm Survey

Eyewitness accounts and several videos confirmed that a tornado
tracked from Baxter to just south of Brookville. Drone footage
confirms the beginning of the track just west of Monrean Rd
approximately 1/4 mile north of Route 28. Widespread and
significant tree damage, including numerous snapped and uprooted
mature trees, was observed in this location. Two residential
structures lost roofs and fascia. The tornado continued eastward
across Route 28 and the Jefferson Cemetery. Nearly complete tree
loss was observed adjacent to and within the cemetery, including
the snapping of numerous mature softwood pines. In addition,
approximately 100 granite gravestones, averaging one foot by two
foot by 4 inches in size, were overturned, with one observed
having rolled 5 times and displaced approximately 15 feet. Drone
footage and ground surveys indicate tree damage continued east
across Red Bank Creek ending prior to Five Mile Run Rd. This is
coincident with tornado video provided via social media. Total
path length for this tornado was approximately 4 miles, with a
path width of at least 200 yards.

Tornado in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:37:00 to 02-OCT-18 16:39:00 (EST-5)
Location: ARMBRUST
Tornado F-scale: EF1
Reported by: NWS Storm Survey

A brief EF1 tornado with max wind of 85-90 mph was documented
from near Ivy Lane and Brinkerton Road to near Pattern Shop Road
and Valley Green Road.
Along Ivy Lane, several softwood tree trunks were snapped, and a
few hardwood trees were uprooted. Farther north along Brinkerton
Road, the tornado strengthened to its peak wind speed as it
descended into a valley and carved a short, focused path of
snapped and uprooted trees.
Tree damage continued after the tornado crossed Brinkerton Road,
but wind speed weakened at this time. The last observed damage was
noted near Pattern Shop Road and Valley Green Road as the tornado
encountered a hillside. A few snapped limbs were noted at the end
of its path.
This tornado was unusual not only for its northward movement in
an eastward-moving storm, but especially because it formed on the
northern side of the parent thunderstorm, removed from the
typical hook echo region.

Tornado in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:55:00 to 02-OCT-18 16:59:00 (EST-5)
Location: RODNEY
Tornado F-scale: EF2
Reported by: NWS Storm Survey

Visible tree damage began on a hilltop west of Stairs Road in
Donegal Township. The tornado intensified rapidly as it descended
into the valley, with widespread blowdown of hardwood and softwood
trees cutting a sharp path through the forest. Drone footage
shows remarkable tree damage in this area with clear convergence in the debris field.
Continuous, but weaker tree damage was found through the valley to
near the intersection of Harr Road and Donegal Lake Road, where
the circulation shrank and weakened.
The blowdown adjacent to Stairs Road was consistent with wind of
110-120 mph, which suggests a peak rating of EF2 for this tornado.

Tornado in WESTMORELAND, PENNSYLVANIA
From 02-OCT-18 16:38:00 to 02-OCT-18 16:40:00 (EST-5)
Location: ARMBRUST
Tornado F-scale: EF0
Reported by: NWS Storm Survey

From eyewitness reports and visible damage, a brief tornado began
near a hilltop along Brinker Road and continued northeastward
toward Rt 819.
Several trees, both softwood and hardwood, in the area of Gold
Leaf Lane were snapped and many others were uprooted. The tornado
grew smaller rapidly as it crossed Rt 819 and leveled trees in the
woods behind homes along Armbrust-Hecla Road before it weakened
quickly. No additional damage points were found by the survey team
after this point.
Tree damage was found along Stone Church Road, but appears to have
been produced by strong wind outside of the tornadic circulation,
perhaps associated with the rear-flank downdraft or a core
collapse in the forward flank of the storm.