A flash flood warning was in effect Thursday morning for Santa Clara, San Mateo and Santa Cruz counties, according to the National Weather Service.
Flash flooding already was occurring, and the warning will remain in effect until 9:15 a.m., the NWS said.
At about 5:20 a.m., Doppler radar indicated heavy rain in Ben Lomond — about 1 to 3 inches of rain had fallen in the area, with additional rainfall amounts of up to 3 inches possible.
The impact includes flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas, the weather service said.
Some locations that will experience flash flooding include Palo Alto, Santa Cruz, Cupertino, Saratoga, Los Gatos, Scotts Valley, Los Altos Hills, Woodside, Boulder Creek, Ben Lomond, Felton, Portola Valley, Monte Sereno and Lexington Hills.
Source: NBC Bay Area