The tornado never touched down in San Francisco. But the conditions in the atmosphere with wind speed and direction were right, said Brian Garcia, warning coordination meteorologist for National Weather Service in the Bay Area. “San Francisco got lucky,” he said.

Powerful storms swept through parts of Northern California on Saturday, knocking down trees, causing widespread power outages and prompting weather officials to issue what they said was the first-ever tornado warning for San Francisco.

Dec. 14, 7 p.m. The San Francisco Recreation and Parks Department has confirmed that 73 trees at city parks were downed as a result of Saturday's storm, with at least 50 of those trees located at the west end of Golden Gate Park.