Scattered showers and thunderstorms develop during the early afternoon hours of July 17, 2021 across western Pennsylvania and in the Lower Susquehanna Valley in an anomalously humid airmass ahead of an approaching cold front. The storms over the Lower Susquehanna Valley developed on a weak boundary in a high CAPE environment, and produced sporadic wind damage before moving to the east. The storms over western Pennsylvania eventually congealed into a broken line that progressed eastward across central Pennsylvania and had imbedded regions of damaging winds and very heavy rain. One hail report was received from beneath a particularly tall cell that developed over Blue Mountain just west of Marysville in Perry County.  Flash flooding from these storms was reported across McKean, Dauphin and Tioga Counties.

Thunderstorm Wind in MIFFLIN, PENNSYLVANIA
From 17-JUL-21 15:43:00 to 17-JUL-21 15:43:00 (EST-5)
Location: MAITLAND
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires east of Burnham.

Thunderstorm Wind in MIFFLIN, PENNSYLVANIA
From 17-JUL-21 15:40:00 to 17-JUL-21 15:40:00 (EST-5)
Location: LEWISTOWN ARPT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees in multiple locations west of Lewistown.

Thunderstorm Wind in SCHUYLKILL, PENNSYLVANIA
From 17-JUL-21 14:23:00 to 17-JUL-21 14:23:00 (EST-5)
Location: FRIEDENSBURG
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees on Moyers Station Road near Friedensburg.

Thunderstorm Wind in CLINTON, PENNSYLVANIA
From 17-JUL-21 16:13:00 to 17-JUL-21 16:13:00 (EST-5)
Location: LOCKPORT
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto Brewery Hollow Road west of Dunnstown.

Thunderstorm Wind in CLINTON, PENNSYLVANIA
From 17-JUL-21 16:03:00 to 17-JUL-21 16:03:00 (EST-5)
Location: BEECH CREEK
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto Monument-Orviston Road in Liberty Township.

Thunderstorm Wind in CLINTON, PENNSYLVANIA
From 17-JUL-21 16:10:00 to 17-JUL-21 16:10:00 (EST-5)
Location: FLEMINGTON
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto Bellefonte Avenue in Lock Haven.

Thunderstorm Wind in NORTHUMBERLAND, PENNSYLVANIA
From 17-JUL-21 16:38:00 to 17-JUL-21 16:38:00 (EST-5)
Location: MILTON
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing winds estimated near 60 mph knocked down a tree onto a home in Milton.

Thunderstorm Wind in PERRY, PENNSYLVANIA
From 17-JUL-21 16:45:00 to 17-JUL-21 16:45:00 (EST-5)
Location: DUNCANNON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A severe thunderstorm producing winds estimated near 60 mph knocked down trees along Watts Drive to the south of Duncannon.

Flash Flood in MCKEAN, PENNSYLVANIA
From 17-JUL-21 13:51:00 to 17-JUL-21 16:00:00 (EST-5)
Location: PORT ALLEGANY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash flooding of several roads in the Port Allegheny area.  A building collapse was also reported from a wash out.

Hail in LANCASTER, PENNSYLVANIA
From 17-JUL-21 13:48:00 to 17-JUL-21 13:48:00 (EST-5)
Location: WITMER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A severe thunderstorm produced quarter-sized hail in Bird-in-Hand.

Hail in PERRY, PENNSYLVANIA
From 17-JUL-21 17:21:00 to 17-JUL-21 17:21:00 (EST-5)
Location: COVE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A severe thunderstorm produced half dollar sized hail northwest of Marysville.

Thunderstorm Wind in NORTHUMBERLAND, PENNSYLVANIA
From 17-JUL-21 17:28:00 to 17-JUL-21 17:28:00 (EST-5)
Location: MC EWENSVILLE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires and uprooted some trees east of Milton.

Thunderstorm Wind in NORTHUMBERLAND, PENNSYLVANIA
From 17-JUL-21 17:15:00 to 17-JUL-21 17:15:00 (EST-5)
Location: KEISER
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires in Kulpmont.

Thunderstorm Wind in ADAMS, PENNSYLVANIA
From 17-JUL-21 17:16:00 to 17-JUL-21 17:16:00 (EST-5)
Location: FAIRFIELD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees in multiple locations between Carroll Valley and Fairfield.

Flash Flood in TIOGA, PENNSYLVANIA
From 17-JUL-21 15:15:00 to 17-JUL-21 18:15:00 (EST-5)
Location: ASAPH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

Flash flooding brought water over several roadways.  In Roseville, Roseville Avenue to Dewalt Road was closed.

Flash Flood in DAUPHIN, PENNSYLVANIA
From 17-JUL-21 17:34:00 to 17-JUL-21 20:00:00 (EST-5)
Location: LENKERVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash flooding resulted in water over multiple roads in Millersburg.

Flash Flood in TIOGA, PENNSYLVANIA
From 18-JUL-21 01:20:00 to 18-JUL-21 03:30:00 (EST-5)
Location: PHILIPS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

Flash flooding brought water and trees across the intersection of State Route 249 and Hollenbaugh Road.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 17-JUL-21 13:07:00 to 17-JUL-21 13:07:00 (EST-5)
Location: LETORT
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Utility Company

A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires in Manor Township.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 17-JUL-21 13:11:00 to 17-JUL-21 13:11:00 (EST-5)
Location: MILLERSVILLE
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Public

A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires near Millersville.

Thunderstorm Wind in CLEARFIELD, PENNSYLVANIA
From 17-JUL-21 14:38:00 to 17-JUL-21 14:38:00 (EST-5)
Location: LUMBER CITY
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees across Lumber City Road, blocking both lanes.

Thunderstorm Wind in PERRY, PENNSYLVANIA
From 17-JUL-21 17:30:00 to 17-JUL-21 17:30:00 (EST-5)
Location: MONTGOMERY FERRY
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing winds estimated near 60 mph knocked down a large tree onto the right lane of Route 11 near Cherry Road.

Thunderstorm Wind in COLUMBIA, PENNSYLVANIA
From 17-JUL-21 15:45:00 to 17-JUL-21 15:45:00 (EST-5)
Location: SHUMANS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A severe thunderstorm producing winds estimated near 60 mph damaged trees near Shumans.

Thunderstorm Wind in LYCOMING, PENNSYLVANIA
From 17-JUL-21 17:26:00 to 17-JUL-21 17:26:00 (EST-5)
Location: RICHARDS GROVE
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto Route 118.

Thunderstorm Wind in CLEARFIELD, PENNSYLVANIA
From 17-JUL-21 14:40:00 to 17-JUL-21 14:40:00 (EST-5)
Location: STONACH
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees near Grampian.

Thunderstorm Wind in LEBANON, PENNSYLVANIA
From 17-JUL-21 13:58:00 to 17-JUL-21 13:58:00 (EST-5)
Location: GREBLE
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees on wires in Jackson Township north of Myerstown.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 17-JUL-21 14:53:00 to 17-JUL-21 14:53:00 (EST-5)
Location: GORDONVILLE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A severe thunderstorm producing winds estimated near 60 mph knocked down trees in Paradise.

Thunderstorm Wind in COLUMBIA, PENNSYLVANIA
From 17-JUL-21 17:23:00 to 17-JUL-21 17:23:00 (EST-5)
Location: PINE SUMMIT
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph knocked down trees near the intersection of Route 42 and Wintersteen School Road.

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 17-JUL-21 18:00:00 to 17-JUL-21 18:00:00 (EST-5)
Location: CHARLTON
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto Devonshire Heights Road in West Hanover Township.

Thunderstorm Wind in NORTHUMBERLAND, PENNSYLVANIA
From 17-JUL-21 16:40:00 to 17-JUL-21 16:40:00 (EST-5)
Location: POTTS GROVE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing winds estimated near 60 mph blew a portion of a barn roof off on North Ridge Road east of Milton.