Thunderstorms, accompanied by flashes of lightning and sudden bursts of rain, caused heavy damage last night to a house in Arlington and knocked out the main power supply to the Air Traffic Control Center in Leesburg, Va.

A lightning strike on the roof of a three story house at 5143 N. 37th Rd. ignited the contents of the attic and caused an estimated $100,000 in damage. No injuries were reported as a result of the blaze, which began about 8:10 p.m.

The storms, which drenched parts of the Washington area for about an hour, beginning at 7:40 p.m. also knocked out a transformer at the air traffic control center, forcing the use of backup power systems.

The center, which controlls air traffic over an area of several thousand square miles, reportedly switched to battery power for about 41 minutes, then began using standby generators.

Although it was reported that communication with the key traffic facility never was lost, a few flights in this area were said to be delayed briefly. Some of the delays were attributed to the storms themselves.

With the passage of a front, thunderstorms were reported last night over a large portion of the Middle Atlantic region.

Portions of southwestern and south central Pennsylvania were struck by tornadoes associated with the thunderstorms. A tornado inflicted injuries and heavy damage in Chambersburg, Pa.

In Washington, today is expected to be hot, with more thunderstorms possible. The National Weather Service predicted the temperature could reach 90, for the first time this year.