The storm swept through Morgan, Berkeley and Jefferson counties in about a half hour, hitting Morgan County first at about 5:15 p.m. and leaving Jefferson County a little before 6 p.m., Goldsmith said.
Weather spotters recorded wind gusts as high as 82 mph, he said.
Wind blew a roughly 30-by-50-foot section of composite roof from the General Motors plant's old paint room onto another part of the roof, causing some damage and springing leaks into the warehouse area, said GM spokesman Kevin Brown.
No one was in the room when it happened, Brown said.
Experts were called in Wednesday to assess roof and any structural damage to the plant, Brown said. Temporary repairs were being made.
Only one storm-related injury was reported, according to emergency services dispatchers.
Kathy Fiddler was taken to Washington County Hospital after lightning struck a tree 15 yards from her back patio door in the Potomac Hills subdivision in northern Berkeley County, according to her daughter, Heather Kave.
Fiddler was treated and later released, according to a hospital spokeswoman.
Road crews were called back to work after their shift and worked into the early morning to remove trees and limbs blocking roads in Berkeley and Jefferson counties, according to state Division of Highways officials.
They were out again a few hours later to start the cleanup, which is expected to take several days, officials said.
The Shepherdstown area was hardest hit in Jefferson County, particularly along River Road, said Jerry Grove, supervisor for county roads.
Marlowe, Falling Waters, Little Georgetown and Whiting's Neck bore the brunt of the storm in Berkeley County, said Bud Donaldson, supervisor of county roads.
Fallen trees and limbs blocked numerous roads and wind blew the roofs off some homes and barns, said Donaldson, who was in the Little Georgetown area during the storm.
About 3,500 homes in the Berkeley Springs and Martinsburg areas and about 100 homes in Washington and Frederick counties were still without power Wednesday afternoon because of downed wires and transformers damaged during the storm, said Allegheny Power spokeswoman Midge Teahan.
Crews, including workers from Winchester, Va., Waynesboro, Pa., and Cumberland, Md., have been working around the clock and were expected to have power restored in Maryland homes by evening and West Virginia homes by 9 a.m. today, Teahan said.
Hugging the Potomac River, the narrow storm caused damage in southern Washington County as well.
Donna Troxler, who lives in the Deer Path development in Knoxville, said the wind was so strong it shifted her two-car garage a couple of inches off its foundation.
Troxler said the storm also damaged patio furniture, buckled siding on her home and ripped a tree out of the ground. She said a neighbor's home had a part of its roof removed and other damage.
Troxler said she was driving near her home when the storm began, forcing her to pull off to the side of the road.
"It looked kind of green. It did. It scared me," she said.
Residents on Taylors Landing Road, near the Potomac River just west of Antietam National Battlefield, reported several uprooted or downed trees along the canal and up the road.
The wind was so strong at one point, it picked up an unoccupied mobile home and turned it upside down, said Mazin Gossard.
"It just missed my son's house. The fence stopped it from going any farther," Gossard said.
Since the trailer is broken up, she said it will probably have to be hauled away as junk.
The wind also took some tin off of the Gossard's home and several tree branches littered the yard, she said.
After looking at the damage and talking to people in Montgomery County, Goldsmith said he was 90 percent sure roll or arc clouds, which can look similar to tornadoes when they dip, were responsible.
While he didn't make it to West Virginia to look at the damage, he said he was pretty sure that was the case with reported funnel cloud sitings near Falling Waters and Shepherdstown.
Staff writers Lisa Graybeal and Guy Fletcher contributed to this story.