Wine country in Sonoma County, California, was among the hardest hit areas, with up to 13 inches of rain since Friday. Rolling hills and vineyards along the scenic route known as River Road were submerged Monday with just the tips of vines visible in completely flooded fields.
The Russian River in Sonoma rose to its highest level since 2006, spilling over its banks and forcing the closure of schools and roads. The weekend storm dumped more than a foot of water on parts of Northern California, forcing hundreds of people to evacuate and leaving thousands without power. The system raised rivers over their banks and toppled trees, among them the fabled giant sequoia dubbed "Pioneer Cabin" 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. Such gaps between storms are "what saves us from the big water," Fire Chief Max Ming said in the Russian River town of Forestville, where rescuers launched rafts and used a helicopter to search for people cut off by rising water. "People hunker down and wait for it to get past."
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.
"It's been about 10 years since we've experienced this kind of rainfall," said Steve Anderson, a National Weather Service forecaster. "We're getting a little bit of a break today, but we have another storm system arriving tomorrow that's not quite as potent but could still cause problems."
Avalanche concerns kept some California ski areas closed for a second day Monday in the Sierra Nevada. Forecasters said more snow and rain was on the way. The Russian River is prone to flooding, but this year's flood has been particularly worrisome because it threatened to topple trees weakened by six years of drought.
A flood warning for the Russian River was in effect, along with a high wind watch planned for Tuesday afternoon and evening, Anderson said. Jeff Watts, an artist, spent an anxious night listening for the sound of falling trees on his property in Forestville. On Monday, he found his drive to work blocked by a car that had slammed into a tree toppled across the road. Emergency crews worked to remove the vehicle.
"I couldn't get past the tree, so I turned around and I'm doing this," said Watts, who had pulled over to photograph oak trees and their reflections in the floodwater. Sacramento River levels swelled so much that state officials planned to open a 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.
Yosemite National Park will reopen the valley floor to day visitors Tuesday after it was closed through the weekend and Monday because of a storm-swollen river, park spokesman Scott Gediman said. Over the weekend, trees crashed against cars and homes and blocked roads in the San Francisco Bay Area. Stranded motorists had to be rescued from cars stuck on flooded roads. The city itself got just over 2 inches of rain.
A giant tree fell across a highway in Hillsborough to the south of San Francisco, injuring a driver who could not stop in time and drove into the tree. And a woman was killed Saturday by a falling tree while she took a walk on a golf course.
To the south near Los Angeles, commuters were warned of possible mudslides in hilly areas. 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.
Winter storm warnings were in effect in the Sierra Nevada until Thursday, with the potential for blizzard and white-out conditions, said Scott McGuire, a forecaster for the National Weather Service based in Reno.
"People need to avoid traveling if at all possible," McGuire said. 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.
Schools were canceled Monday in Reno and Sparks, and Gov. Brian Sandoval told all nonessential state government workers to stay home after he declared a state of emergency. After touring the two cities, Sandoval said no serious injuries were reported during the flooding.
"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."
Gecker reported from San Francisco. Associated Press writers Janie Har in San Francisco, Christopher Weber in Los Angeles, Scott Sonner in Reno, Colleen Slevin in Denver and Scott Smith in Fresno also contributed to this report.