[Weather Alert] More storms to strike West Coast

Northern California and Nevada braced for another powerful storm after getting lashed by downpours that flooded roads, homes and vineyards and toppled a storied giant sequoia.

Parts of Northern California were soaked by more than a foot of rain over a 72-hour period that ended early Monday, forcing hundreds of people to evacuate and leaving thousands without power. The heavy rains forced rivers out of their banks and toppled trees, among them the famed “Pioneer Cabin” in Calaveras Big Trees State Park that had a drive-thru tunnel carved into its base more than a century ago.

Another strong storm was bearing down on the region and expected to hit Tuesday.

Emergency crews in rescue boats and helicopters took advantage of a one-day respite from the rains later Monday to rescue stranded people and assess damage after a weekend of stormy weather that authorities called the heaviest rain in a decade.

In the Sierra Nevada mountains, a winter storm warning was in effect until Thursday morning with the potential for blizzard and white-out conditions, said Scott McGuire, a forecaster for the National Weather Service based in Reno, Nevada.

Four to 8 feet of snow are forecast through Thursday above 7,000 feet, and the Lake Tahoe area could get between 2 to 5 feet of snow, he said.

“People need to avoid traveling if at all possible,” said McGuire. Avalanche concerns kept some California ski areas closed for a second day Monday in the Sierra Nevada.

In the San Francisco Bay Area, a coastal flood advisory was in effect from Tuesday through Friday, with a forecast for up to 7-foot “king tides” that could pose a flooding risk for coastal roadways, said Steve Anderson, a National Weather Service forecaster in Monterey, California.

Flood warnings and a high-wind watch was also in effect Tuesday for the Russian River, which rose to its highest level since 2006 and spilled over its banks early Monday, flooding roads and vineyards and forcing schools to close across the area.

“It’s been about 10 years since we’ve experienced this kind of rainfall,” Anderson said Monday. He said the storm system arriving Tuesday was not as potent as over weekend but could still cause problems. “The big concern is flash flooding, rapid rises on creeks and the Russian River coming out of its banks again.”

Parts of California’s wine country in Sonoma County were among the hardest hit, with up to 13 inches of rain from Friday-early Monday. Rolling hills and vineyards along the scenic route known as River Road were submerged Monday with just the tips of the vines visible in completely flooded fields.

Melba Martinelli, who lives in the Russian River town of Guerneville, was wading through her yard Monday in knee-high rain boots, surrounded by flooded streets.

“I’m watching the water come up higher and higher, and my boots are almost going underwater now,” Martinelli said. “The river is coming up the street now. It’s pretty scary.”

In nearby Forestville, rescuers launched rafts and used a helicopter to search for people cut off by rising water. Authorities said the mostly dry conditions Monday were a relief.

Such gaps between storms are “what saves us from the big water,” Forestville Fire Chief Max Ming said. “People hunker down and wait for it to get past.”

To the south near Los Angeles, commuters were warned of possible highway flooding and mudslides in hilly areas.

The back-to-back storms that hit California and Nevada since last week are part of an “atmospheric river” weather system that draws precipitation from the Pacific Ocean as far west as Hawaii. That kind of system, also known as the “pineapple express,” poses catastrophic risks for areas hit by the heaviest rain.

Despite the bad weather in some parts, Yosemite National Park was forecasting a return to normal. The park planned to reopen the valley floor to visitors Tuesday morning after it was closed through the weekend and Monday because of a storm-swollen river, park spokesman Scott Gediman said. He said guests will be allowed back in starting at 8 a.m. for day visitors. Park workers were checking the extent of damage from the storm to water and sewer systems, he said.

Sacramento River levels swelled so much that state officials planned to open the weir located upstream from Sacramento’s Tower Bridge for the first time in more than a decade. The weir is a barrier of 48 gates that must be opened manually to protect the city of Sacramento from floodwaters.

Emergency workers in Nevada voluntarily evacuated about 1,300 people from 400 homes in a Reno neighborhood as the Truckee River overflowed and drainage ditches backed up.

Schools were canceled Monday in Reno and Sparks, and Gov. Brian Sandoval told all nonessential state government workers to stay home Monday after he declared a state of emergency.

After touring the two cities, Sandoval said no serious injuries were reported during the flooding, which authorities had feared might be the worst in a decade.

“It’s bittersweet because it wasn’t as bad as it could have been,” Sandoval said. “But to those people affected, it was really hard on them.”

The Associated Press contributed to this article.