A massive storm barreled toward Southern California on Monday after flooding highways, toppling trees and causing rock slides and mud flows in areas burned bare by wildfires across the northern half of the state.
Drenching rains and strong winds accompanied the weekend arrival of an atmospheric river — a long plume of Pacific moisture — into the drought-stricken state.
Rainfall records were shattered and heavy snow pounded high elevations of the Sierra Nevada. The National Weather Service peppered the state with flash flood warnings.
Flooding was reported across the San Francisco Bay Area, closing streets in Berkeley, inundating Oakland’s Bay Bridge toll plaza and overflowing rivers in Napa and Sonoma counties. Power poles were downed and tens of thousands of people in the North Bay were without electricity.
“It’s been a memorable past 24 hours for the Bay Area as the long talked-about atmospheric river rolled through the region,” the local weather office said. “We literally have gone from fire/drought conditions to flooding in one storm cycle.”
The weather service called preliminary rainfall totals “staggering,” including 11 inches (27.9 centimeters) at the base of Marin County’s Mount Tamalpais and and 4.02 inches (10.2 centimeters) in downtown San Francisco.
“It looks like yesterday was the 4th wettest day ever for downtown SF where records go back to the Gold Rush years,” the weather service said.
About 150 miles (241 kilometers) to the north, the California Highway Patrol closed a stretch of State Route 70 in Butte and Plumas counties because of multiple landslides within the massive Dixie Fire burn scar.
“We have already had several collisions this morning for vehicles hydroplaning, numerous trees falling, and several roadways that are experiencing flooding,” the highway patrol’s office in Oroville tweeted on Sunday. “If you can stay home and off the roads today, please do. If you are out on the roads, please use extreme caution.”
The same storm system also slammed Oregon and Washington state, causing power outages affecting tens of thousands of people. Two people were killed when a tree fell on a vehicle in the greater Seattle area. Eastside Fire & Rescue responded to the scene of the fatalities near Preston, Washington, which is about 20 miles (32 kilometers) east of Seattle.
In California’s Colusa and Yolo counties, state highways 16 and 20 were shut for several miles due to mudslides, the state Department of Transportation said.
Burn areas remain a concern, as land devoid of vegetation can’t soak up heavy rainfall as quickly, increasing the likelihood of flash flooding.
“If you are in the vicinity of a recent burn scar and haven’t already, prepare now for likely debris flows,” the Sacramento weather service tweeted. “If you are told to evacuate by local officials, or you feel threatened, do not hesitate to do so. If it is too late to evacuate, get to higher ground.”
South of San Francisco, evacuation orders were in effect in the Santa Cruz Mountains over concerns that several inches of rain could trigger debris flows in the CZU Lightning Complex Fire burn scar when the storm moves through early Monday. Further south, parts of western Santa Barbara County saw evacuation warnings upgraded to orders in the area burned by this month’s Alisal Fire.
Strong winds were also expected, with gusts of up to 60 mph (97 kph) at the windiest spots in Northern California. Elevations above 9,000 feet (2,745 meters) in the Sierra Nevada could get 18 inches (46 centimeters) of snow or more from Sunday until Monday morning.
Recent storms have helped contain some of the nation’s largest wildfires this year. But it remains to be seen if the wet weather will make a dent in the drought that’s plaguing California and the western United States. California’s climate is hotter and drier now and that means the rain and snow that does fall is more likely to evaporate and less likely to absorb into the soil.
California’s 2021 water year, which ended Sept. 30, was the second driest on record and last year’s was the fifth driest on record. Some of the state’s most important reservoirs are at record low levels.