Several rounds of scattered thunderstorms developed in a low shear, moderate CAPE, high DCAPE environment. The first round developed as scattered convection in southwest PA on the previous night and crossed into central PA by 11 AM EDT on Aug 10. Convection took on a linear mode with bowing characteristics as it approached Dauphin County by 2 PM EDT and ultimately produced damaging winds. Additional rounds of convection developed upstream later in the afternoon and again took on linear and bowing characteristics as it approached the Lower Susquehanna Valley by the evening hours. This line of storms converged with another line of storms moving northeastward from Virginia and Maryland. Although wind shear was weak, DCAPE values of near 1000 J/kg and storm motion near 15 kts allowed for damaging straight line wind to develop. There were no reports of hail.

Thunderstorm Wind in YORK, PENNSYLVANIA
From 10-AUG-21 17:25:00 to 10-AUG-21 17:25:00 (EST-5)
Location: HANOVER
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing wind estimated near 60 mph downed trees on Stock St and on McCosh St in Hanover, PA.

Thunderstorm Wind in YORK, PENNSYLVANIA
From 10-AUG-21 17:35:00 to 10-AUG-21 17:35:00 (EST-5)
Location: LINCOLNWAY
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 powerlines in West York, PA.

Thunderstorm Wind in YORK, PENNSYLVANIA
From 10-AUG-21 17:36:00 to 10-AUG-21 17:36:00 (EST-5)
Location: YORK
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 powerlines in York, PA.

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 10-AUG-21 13:25:00 to 10-AUG-21 13:25:00 (EST-5)
Location: DAUPHIN
Magnitude: 61.00 EG
Property damage: 6.00K
Crop damage: 0.00K
Reported by: Public

A severe storm producing winds estimated near 70 mph uprooted and snapped half a dozen to a dozen large trees on and near a property off Stricker Lane. The storm also ripped shingles off a shed on the property.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 10-AUG-21 17:46:00 to 10-AUG-21 17:46:00 (EST-5)
Location: LITITZ
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing winds estimated near 60 mph brought down powerlines 1 mile SE of Lititz.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 10-AUG-21 18:39:00 to 10-AUG-21 18:39:00 (EST-5)
Location: BARTVILLE
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A severe thunderstorm producing wind estimated near 60 mph brought down numerous utility wires across the area.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 10-AUG-21 17:50:00 to 10-AUG-21 17:50:00 (EST-5)
Location: (LNS)LANCASTER ARPT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A severe thunderstorm produced a 59 mph wind gust, recorded at Lancaster Airport.

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 10-AUG-21 13:35:00 to 10-AUG-21 13:35:00 (EST-5)
Location: INGLENOOK
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 downed trees near Clarks Valley Road.

Thunderstorm Wind in YORK, PENNSYLVANIA
From 10-AUG-21 17:15:00 to 10-AUG-21 17:15:00 (EST-5)
Location: SPRING GROVE
Magnitude: 52.00 EG
Property damage: 14.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A severe thunderstorm producing winds estimated near 60 mph knocked down a few large trees on a property in Spring Grove, PA. Winds from this storm also resulted in the partial collapse of a garage.