SAN FRANCISCO (KTVU & AP) -- A Flash Flood Watch for San Francisco and other parts of the Bay Area has been issued until 11 p.m. on Sunday.
Urban flooding may occur in areas that have historically flooded. Areas near small creeks and streams are most at risk.
San Francisco residents may receive up to 10 free sandbags each at 2323 Cesar Chavez Street.
Residents of California from the coastline to the Sierra Nevada are bracing for heavy rain and snow that's already shut down Yosemite National Park and is expected to swell area rivers, flood Bay Area streets and topple trees.
Rangers at Yosemite on Friday closed access to the valley floor, raising memories of flooding in 1997 that forced the park to shut down for two months.
On the coast in Santa Cruz -- where up to a foot of rain could fall in places -- officials have set up sand bag stations for residents.
"We're giving them a shovel and the sand and showing them how to fill them up," said Jason Hoppin, a Santa Cruz County spokesman. "We haven't seen rain like this in a long time."
In San Francisco, many residents rushed to find galoshes and umbrellas while crews braced for another round of power outages.
And SFPUC trucks spent much of Friday removing leaves and debris out of city storm drains.
"They have elephant-like looking trunks [which] remove the grate off the catch basins," said Idil Bereket with the city Water Department.
For weeks, crews have been kept busy by working to remove debris from the 25,000 catch basins and over 1,000 miles of sewer pipes throughout the city, but now that a massive storm is bearing down on San Francisco, they're working at breakneck speed.
"Fortunately, we put in a sump pump a few months ago which has been a lifesaver," said Regina Faustine, who lives in San Francisco.
Residents and crews were working to stave off potential flooding any way they could. There was a steady stream Friday of customers at the city Public Works yard on Kansas Street, near Highway 101 and Cesar Chavez Drive, who were looking to stock up on sand bags.
Officials said the location had doled out at least 800 free sandbags within a five-hour period on Friday.
"Once a year it floods pretty bad, once every three years it floods really bad, said Julia Jet, who works at a leather shop on 17th and Folsom streets, a spot notorious for sewage backups during heavy rains.
"When the rains come what we do is lift everything up like a foot, we put bins on tables."
"It will [flood] 8-10, maybe 12 inches," said Cleto Gonzalez, adding that Folsom Street looks more like a lake than a road when storms hit. "You're here for 4-6 months cleaning and it's an absolute disaster," he said.
The city is expected to install temporary barriers soon to help ease the flooding, but many owners along Folsom say the city needs to do more.
"It takes like six months to get back up on your feet again," Gonzalez said. "But we'd just rather it not happen."
The city's Public Works department plans to bring in extra arborists, general laborers and dispatchers around the clock through the weekend. And there will be engineers and street inspectors on call in case of any mudslides or sinkholes. The sandbag giveaway has been extended until Sunday, daily hours run from 8 a.m. to 2 p.m.
The heavy rains come as California enters a sixth year of drought, starting in October with more rain falling than in three decades, mostly in Northern California. Los Angeles is experiencing the wettest winter in six years, forecasters say.
Forecasters anticipate the storm surge stretching from Hawaii in the Pacific -- called an atmospheric river -- could dump up to eight inches of rain from Sonoma to Monterey counties. Forecasters warn of mudslides on the Central Coast hard hit this summer by scarring wildfires.
The storm's mild temperatures will drive up the snowline to above 9,000 feet throughout the Sierra Nevada, causing runoff in the lower elevations, said Zach Tolby, a meteorologist with the National Weather Service in Reno.
The Truckee River, which flows from Lake Tahoe and through Reno, is forecast to rise to its highest point in more than a decade, according to the National Weather Service, which has issued a flood warning.
Mammoth, which is at a higher elevation in the Southern Sierra, could receive up to eight feet of snow, Tolby said, adding that another storm early next week could deliver another three feet of snow.
Access to Yosemite's valley will close at 5 p.m. Friday ahead of stormy conditions beginning early Saturday. Other parts of the park will remain open, but rangers caution visitors to be aware of ice and debris on the roads. The closure is expected at least Sunday through, officials said.
Early Friday, Yosemite spokeswoman Jamie Richards said that rangers stood watch for flooding along the Merced River, a major river flowing through the towering granite peaks.
"We're prepared," said Richards, adding that they're accustomed to life in a giant canyon with frequent, rain, snow, ice and rock falls. "We have a lot of things we deal with on a frequent basis."
Rangers are keeping an especially close eye on Pohono Bridge, which crosses the Merced River deep in Yosemite Valley. Richards said that flooding there starts when the water level reaches 10 feet, but on Thursday the watermark hit just four feet.
A large storm in 1997 flooded Yosemite Valley, closing the park for two months and washing out roads, lodging and campgrounds.
Rangers don't expect damage like they experienced 20 years ago because the snowpack isn't as deep. They've moved buildings away from the river, and increased drainage, Richards said.
"What happened in 1997 is not a comparison with what's happening today, she said.
KTVU reporter Tara Moriarty contributed to this report.