Flood advisories are in effect across the Bay Area as a storm system moves through the region this evening, according to the National Weather Service. The city of San Francisco and northern San Mateo County, including the cities of San Bruno, Pacifica and Millbrae, are under an advisory until 6:45 p.m., the weather service said. An advisory for western Santa Cruz County will run through 7:15 p.m. and includes the cities of Boulder Creek and Ben Lomond, according to the weather service.