San Francisco residents woke up to a tornado warning early Saturday morning as a powerful storm system hit the area with heavy rain and strong winds.
It was the first-ever tornado warning for San Francisco, but not the first tornado, CBS News Bay Area meteorologist Paul Heggen cited.
The National Weather Service issued a warning for northern San Mateo County and parts of downtown San Francisco from just before 6 a.m. until 6:15 a.m.
According to the NWS, there was a cyclone signature on the radar that produced enough of a rotational signature to trigger the warning.
“Radar analysis at 5:52 a.m. clearly shows a ‘hook echo’ offshore – this is the signature we look for to identify a developing tornado. This feature was embedded in a large area of very heavy rain, but it always stands out,” Heggen said. explain.
The NWS Bay Area declared the warning ended for San Francisco at 6:07 a.m. and let the tornado warning expire at 6:15 a.m.
The warning sparked a wave of posts on social media from residents who were awakened by the alert on their cell phones. This was the first ever tornado warning issued for San Francisco.
A special alert was also issued for a possible downpour over San Francisco Bay in the Bay Bridge area, which expired ten minutes after the tornado warning.
Although the strongest part of the system has passed, isolated severe thunderstorms remain possible in parts of the Bay Area throughout the morning, the National Weather Service said.
The risk of a severe storm is marginal and the NWS said it would only last until Saturday morning. Storm conditions caused power outages for thousands of people in the Bay Area, according to PG&E.
