Winds gusting up to 55 miles an hour knocked out power for 20,000 PECO customers across the Philadelphia suburbs Saturday, while leaving power lines in the city relatively unscathed.

There were reports that the gusts had tipped over an empty tractor-trailer near the Walt Whitman Bridge. Trees and tree limbs were down in many locations.

The National Weather Service said the winds, spawned by the same Canadian storm that initially visited warm days on the area, should subside throughtout the day, but that high-wind warnings would be in effect until by 9 p.m.