Washington's temperature soared to a balmy 71 degrees yesterday, only 6 degrees below the record, before a cold front swept in, bringing thunder, lightning, high winds and hail that rattled on the roofs of homebound commuters' cars.

The clash between the unusually warm air that was arriving helped produce the thunderstorm and hailstones that are more frequently associated with spring and summer, according to National Weather Service forecaster David Gustin.

The storm, which swept through the area between 3:30 and 5 p.m., caused only a few scattered power failures in Maryland and the District of Columbia, and only one minor failure in Northern Virginia, according to utility company spokesmen.

Effects on traffic were also reported as slight, with area police departments reporting a few more than the average number of minor accidents.

Perhaps the most vivid effects of the storm were produced by the weather itself. At 1:40 p.m. the temperature reached 71 degrees at the official measuring station at National Airport. The record for the date is 77, set in 1896.

As the cold air arrived and clouds darkened the skies, the mercury plunged from a sunny 70 degrees at 3 p.m. to 50 degrees - once degree above normal for the date - at 4 p.m.

Hailstones ranging in size from one quarter to three eightss of an inch in diameter were reported in several sections of the metropolitan area, including Alexandria, Prince George's County and Washington.

Apparently there was no damage. "We had quite a bit of hail," the Virginia State Police at Alexandra reported. "It didn't do anything but just fall."