As winter storms with relentless rains and heavy winds hammer the state, California's Gov. Gavin Newsom declared a state of emergency in Los Angeles, Orange, Riverside, San Bernardino, San Diego, and Shasta counties.
The declaration will enable emergency authorities and open up resources for response teams.
Across the region, the devastating impact of downpours fueled by atmospheric rivers are beginning to be seen.
Local reports include awreckinvolving a FedEx truck carrying 12,000 pounds of packages that shut down northbound lanes on Interstate 5 in Ventura County.
The San Bernardino County Fire Department announced that Highway 2 is impassable and issued an evacuation warning for communities near San Bernardino Mountain.
High water has made portions of Interstate 5 and the Ventura Freeway in the Los Angeles area impassable.
Topanga Canyon Boulevard north of Highway 1 in Malibu, which has been under construction since the Palisades Fire, has beenshut downentirely through Friday, at least.
In Northern California, snowy conditions have putchain control into effecton I-80 over Donner Summit.
More than 140,00 customers are without power according to PowerOutage.us.
California officials and weather forecasters urged holiday travelers to avoid the roads and reconsider Christmas travel.
Storms began to move in late Tuesday evening and were expected to intensify into Christmas Eve. Authorities said the millions of people expected to travel across the state will likely meet hazardous, if not impossible, conditions as several atmospheric rivers were forecast to make their way through the state, the National Weather Service warned.
"If you're planning to be on the roads for the Christmas holidays, please reconsider your plans," said Ariel Cohen, a National Weather Service meteorologist in Los Angeles, during a Tuesday news conference.
Forecasters saidSouthern California could see its wettest Christmas in yearsand warned about flash flooding, mudslides and debris flows in areas scorched by last January'swildfires. Los Angeles County officials said they were knocking on the doors of some 380 particularly vulnerable households to order them to leave.
Heavy rain and flash flooding already led to water rescues and at leastone death in Northern California, local officials said. Shasta County Sheriff Michael L. Johnson on Monday declared a state of emergency to prepare for more rain and allow the state to help with hazard mitigation and search and rescue operations.
Southern California typically gets half an inch to 1 inch of rain this time of year, but this week many areas could see between 4 and 8 inches, National Weather Service meteorologist Mike Wofford said. It could be even more in the mountains. Gusts could reach 60 to 80 mph in parts of the central coast.
Officials expect multiple road closures and airport delays during the storms. Downed trees and power lines are also possible. Parts of Los Angeles are under evacuation warnings this week.
The county put up K-rails, a type of barrier, around the burn scar to help catch sliding debris during rainstorms. Residents could also pick up free sandbags to protect their homes, said Kathryn Barger, a Los Angeles County supervisor representing Altadena.
Many people in burn scar areas decided not to leave after receiving the evacuation notification, Los Angeles Police Department Chief Jim McDonnell said. He urged them to reconsider.
"The threat posed by this storm is real and imminent," he said.
Local and state officials are gearing up to respond to emergencies through the week. The state has deployed resources and first responders to a number of counties along the coast and in Southern California. The California National Guard is also on standby to assist.
An atmospheric river is a long, narrow band of water vapor that forms over an ocean and flows through the sky, transporting moisture from the tropics to northern latitudes.
The Associated Press contributed to this report.