Violent storms rock Greater Boston

Lightning sparks fires and 20,000 go without power

Mark Parsons returned to his home in Newton and found that a tree had been uprooted by yesterday's violent storm. NStar customers lost power - mostly in Newton, Watertown, and Waltham - largely because of trees or limbs falling on power lines, (Essdras m suarez/globe staff)

A violent thunderstorm tore through Greater Boston yesterday afternoon, causing flash floods, pelting pedestrians with pea-size hail, knocking out power, and uprooting trees with wind gusts exceeding 55 miles per hour.

Lightning strikes set off fires in the penthouse of a seven-story Beacon Street building in the Back Bay and a three-family house on Pearl Street in Cambridge. Flash floods caused the eastbound lanes of Storrow Drive, near Kenmore Square, to be shut down, and a sink hole on Route 9 in Brookline forced a closure there.

About 20,000 NStar customers lost power - mostly in Newton, Watertown, and Waltham - largely because of trees or limbs falling on power lines, said Kate Leonard, a company spokeswoman. Power was restored for most customers by the evening.

Two-thirds of an inch of rain fell at Logan International Airport in roughly 30 minutes, said Bill Simpson, a forecaster with the National Weather Service in Taunton. He said the low number can be misleading in characterizing the storm's ferocity. Wind gusts at Harvard Bridge topped out at 57 miles per hour.

"It's not how much rain falls," he said, "it's the intensity of the storm."

The two-alarm Beacon Street fire, which was reported at 2:50 p.m., caused $5 million in damage and sent four firefighters to the hospital with minor burns and heat exhaustion, said Steve MacDonald, Fire Department spokesman.

Sergio Coelho, 46, lives on the second floor of the building and was watching the storm with his 12- and 14-year-old daughters from a window that overlooks the Charles River. They saw the sky light up when the lightning struck the building.

"It sounded like a big, big thunderbolt, like an enormous whip," said Coelho, adding that they had no idea the building had been struck until the fire alarms sounded five minutes later.

In Cambridge, lightning hit the roof of a Pearl Street house at about 2:20 p.m., and flames were shooting out when firefighters arrived. No one was injured in the two-alarm blaze, which caused about $250,000 in damage, said Deputy Fire Chief Stephen Leonard.

The National Weather Service said Cambridge was also hit by a microburst, which is a localized downdraft that produces very strong, but brief, wind shears.

The Coast Guard, Environmental Police, Massachusetts Port Authority, and the State Police sent boats when eight sailboats with 57 people aboard from the Piers Park Sailing Center signaled they were in distress during the storm, said Petty Officer Lauren Jorgensen, a Coast Guard spokeswoman.

No one was injured, though some people had to be transferred to the State Police boat and taken to shore, Jorgensen said.

Globe correspondents Matt Collette, Kate Augusto, and Jillian Jorgensen contributed to this report.