Rain is expected to move into the region late Thursday night, beginning in the North Bay and spreading south on Friday.
The series of Bay Area storms could drop as much as 10 to 12 inches of rain through the weekend, according to the National Weather Service.
"The last storm was fairly intense but fairly brief," National Weather Service meteorologist Bob Benjamin said. "This (upcoming) storm is just as intense, and it will be more prolonged."
This storm system is expected to bring between 2 to 4 inches of rain to the North Bay and 1 to 3 inches of the wet stuff in more southern areas, including San Jose.
Winds are already starting to pick up in Oakland and Concord, which were reporting gusts around 15 mph Thursday afternoon, Benjamin said.
There are some reports of light rain in those areas, but during the next several hours, Benjamin said, the rain will increase steadily, with the heaviest rain and wind expected to hit around midnight.
Starting at 7 p.m. Thursday and remaining in place through Friday afternoon, a flash flood watch begins in the coastal North Bay and mountainous areas, parts of the Monterey Bay area, the Peninsula and San Francisco, and Santa Cruz Mountains because of several inches of rain expected in those areas, according to the National Weather Service.
In preparing for the storm, the U.S. Coast Guard is reminding mariners to be aware of high winds and heavy seas into Friday. A small craft advisory and a gale warning are in effect for parts of the central and northern coast as the potential storm will produce strong southerly winds, endangering mariners and setting vessels adrift, according to the Coast Guard.
Boaters should also check mooring and anchoring as vessels can break free from worn or insufficient lines, or an improperly sized anchor or anchor chain. The Coast Guard is also warning people and their pets to avoid low-lying beaches, jetties and rocky areas during the storm.
By Friday night, the Bay Area is expected to catch another break from the wet stuff into early Saturday, according to the weather service. But not for long. A significant storm is expected to hit the region late Saturday, with several more inches of rain expected.
The storm system that moved across the Bay Area on Wednesday dropped between a quarter-inch to 2 inches of rain in the region.
San Jose had .16 inches of rain Wednesday, bringing its annual total to 1.62 inches, about 59 percent of average for this time of year. Los Gatos received a half-inch of rain.
Oakland had .27 inches of rain, bringing its annual total to 3.15, about a half-inch below normal for this time of year. In San Francisco, .38 inches of rain fell.
The Sierra Nevada is also being hit by the storms and is expected to receive as much as 3 feet of snow in higher elevations, according to the weather service. Heavy, wet snow is expected to accumulate over the passes around Lake Tahoe.
Staff writer Katie Nelson contributed to this story. Contact Mark Gomez at 408-920-5869. Follow him on Twitter @MarkMgomez and Reach Kristin J. Bender at email@example.com. Follow her at Twitter.com/kjbender.