A first-ever tornado warning was issued for San Francisco County Saturday morning as thunderstorms and wind gusts of up to 60 mph swept through the area, officials said.
“Take shelter now in a basement or interior room on the lowest floor of a sturdy building,” a National Weather Service advisory on social media warned. Parts of San Mateo County were also included in the warning.
More than a million people were subject to the brief warning, which was issued at 5:51 a.m. and lifted at 6:15 a.m., said Lamont Bain, a meteorologist with the National Weather Service Bay Area.
The advisory was the first time the agency issued a tornado warning for San Francisco County, he said. San Mateo County last received a tornado warning on March 18, 2011.
“It’s certainly unusual. We don’t see the ingredients coming together all the time to cause tornadoes,” Bain said.
In addition to humidity, “you need a combination of lift, some instability and some wind shear. We saw all of these things come together for a brief period this morning.
He said the tornado warning was “a good reminder that people still have multiple ways” to receive weather information and alerts. This includes signing up for text alerts, checking news reports, and listening to weather radio.
Rain showers are forecast for the rest of the day in San Francisco, with wind gusts of 30 to 35 miles per hour at least until noon. The rain should stop tonight, with dry weather on Sunday before another dose of rain on Monday.
