SACRAMENTO, Calif. — Strong winds from a winter storm that began churning across Northern California on Friday tore the roof off a business and downed power lines in the San Francisco Bay area, while downpours prompted flood warnings for low-lying areas.

SACRAMENTO, Calif. — Strong winds from a winter storm that began churning across Northern California on Friday tore the roof off a business and downed power lines in the San Francisco Bay Area, while downpours prompted flood warnings for low-lying areas.

A second storm packing a similar punch was forecast to hit a wider swath of the state on Sunday, with high water levels projected as far south as San Diego.

The National Weather Service issued a flood watch for much of the Central Valley through Sunday and a winter storm warning through early today for the Sierra Nevada, where as much as 3 feet of snow is predicted by this morning.

Travel through the mountains is expected to be treacherous, with winds up to 50 mph through the passes and snow levels dropping to 3,000 feet elevation by early this morning. The Sierra Avalanche Center in Truckee predicted a considerable danger of snow slides. Tree-toppling gusts of 35-45 mph were forecast throughout the Central Valley and Sierra foothills, putting utility crews on alert.

Thunderstorms that moved through the San Francisco Bay Area on Friday were blamed for a powerful wind burst that downed power lines and tore away a 150-foot section of a tin roof covering a landscaping business in Santa Rosa. No injuries were reported.

A tornado warning was issued briefly for San Mateo County, but the weather service had no reports of any twisters. There is no relief in sight after an already soggy week, with periods of rain expected to last through next week.

"We're kind of socked in for an unsettled wet period," National Weather Service meteorologist Eric Kurth said.

State and federal agencies are dumping more water from Northern California reservoirs to make room for mountain runoff, but officials say no major rivers are in danger of flooding. It helps that much of the precipitation is falling in the form of snow, said California Department of Resources spokesman Ted Thomas.

The U.S. Bureau of Reclamation increased the flow from Lake Shasta on the northern Sacramento River and Folsom Lake east of Sacramento. The state Department of Water Resources boosted flows from Lake Oroville 70 miles north of the state capital.

As a result, Sacramento River water was spreading into the Sutter and Yolo bypasses, low-lying areas north and west of the state capital that are set aside to handle excess water and reduce the danger of flooding.

The high volume of water covered portions of parks and bicycle trails through flood plains in Sacramento and Redding. Sacramento shut flood gates at Del Paso Boulevard along the American River for the first time since 2006, requiring drivers to take a detour.

Isolated mudslides and creek flooding are expected to continue throughout the state.

The most noticeable effect of the wet weather in Northern California is along the coast, where a 40-foot section of Highway 1 south of Carmel slid into the ocean on Wednesday.

Engineers are trying to figure out how to open the two-lane coastal highway that leads to the scenic Big Sur region after the collapse near Rocky Creek Bridge.