Tonight's Exciting Weather!

The meteorology was jamming this evening as the low pressure center approached San Francisco. Not only was "bombogenesis" (a rapid reduction in pressure) going on, but the low pressure center resolved itself into two (and possibly three) low pressure centers, all rotating around each other (called the "Fujiwhara Effect"). 

Here is a GOES-West visible picture from about 5:51 PDT, showing two centers spinning around each other like figure skaters. Thunderstorms and high winds occurred over a wide area! Rather rare for the greater Bay Area. 

The main thrust of the storm is still in Southern California, however. More here:

On Tuesday afternoon, as the storm approached the Bay Area, the system developed two “eyes,” or areas of low pressure, resulting in a “doubled-barreled blow” to San Francisco and Santa Cruz, said Bay Area National Weather Service meteorologist Brian Garcia. 

The rare occurrence, known as the Fujiwhara effect, intensified winds as the low-pressure areas danced around each other. 

Rick Canepa, a National Weather Service meteorologist in Monterey County, cited the two low-pressure centers “and possibly a third one that are just kind of rotating around each other.” 

The phenomenon was contributing to peak gusts upward of 60 to 75 mph in the Santa Cruz Mountains, Canepa said, with 50- to 60-mph winds across Santa Cruz and Santa Clara counties.