Residents of San Francisco received a tornado warning early Saturday morning as a powerful storm system brought heavy rain and wind to the region. This warning, issued by the National Weather Service (NWS), marked the first-ever tornado warning for the city.
The alert was communicated for northern San Mateo County and parts of downtown San Francisco shortly before 6 a.m. and remained in effect until 6:15 a.m. The NWS reported a cyclonic signature on radar that indicated sufficient rotation to warrant the warning.
At 5:52 a.m., radar scans revealed a 'hook echo' offshore, a signature indicative of a developing tornado. Although embedded within a larger area of heavy rain, this feature was prominent enough to raise concerns.
The warning was lifted at 6:07 a.m., with the official expiration at 6:15 a.m. The alert prompted numerous social media reactions from residents, many of whom were startled by the notification on their devices.
A separate alert concerning a potential waterspout on San Francisco Bay was also issued but expired shortly after the tornado warning. Following the storm's peak, isolated severe thunderstorms could still occur in parts of the Bay Area throughout the morning, according to NWS forecasts.
The storm caused power outages affecting thousands in the region, as reported by PG&E.