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.

For the first time in recorded history, downtown San Francisco was issued a tornado warning on Saturday as severe storm conditions swept through the city, prompting local authorities to warn residents of the rare threat.