California is bracing for a soggy holiday season as meteorologists predict up to eight inches of rain will drench parts of the state, including Los Angeles County and Santa Barbara, over the coming four days.

State officials are advising travelers to steer clear of the roads due to a series of winter storms that threaten to bring flash floods and even tornadoes.

The storm system began its advance Tuesday night and is expected to grow more severe through Christmas Eve. By Christmas Day, a ‘clipper’ weather pattern is predicted to blanket much of the West Coast and Midwest with rain and snow.

Los Angeles is expected to bear the brunt of the storms, with a severe flood warning in effect until noon on Wednesday. Residents in flood-prone areas have been urged to evacuate and head to higher ground immediately.

Authorities caution that the millions planning to travel within California for the holidays will likely encounter dangerous, if not impassable, conditions, as multiple atmospheric rivers are set to sweep across the state.

‘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 said Southern California could see its wettest Christmas in years and warned about flash flooding, mudslides and debris flows in areas scorched by last January’s wildfires. 

Los Angeles is expected to be especially hard hit by the incoming winter storms, with a severe flood warning in place for the area until 12pm on Wednesday. Hundreds of residents in at-risk neighborhoods have been warned to ‘immediately move to higher ground’

The holiday period is forecast to be a washout for the Golden State this year, with meteorologists warning that up to eight inches of rain is expected to hit several areas including Los Angeles County and Santa Barbara (Pictured: Menlo Park, CA, on December 24)

Los Angeles County officials said they were knocking on the doors of some 380 particularly vulnerable households to order them to leave. 

Much of the Sacramento Valley and the San Francisco Bay Area were under a flood watch and a high wind warning through Friday.

Forecasters warned heavy snow and gusts were expected to create ‘near white-out conditions’ Wednesday in parts of the Sierra Nevada and make it ‘nearly impossible’ to travel through the mountain passes.

There’s also a risk of severe thunderstorms and a small chance of tornadoes along the northern coast.

Heavy rain and flash flooding already led to water rescues and at least one 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 (1.3 to 2.5 centimeters) of rain this time of year, but this week many areas could see between 4 and 8 inches (10 to 20 centimeters), National Weather Service meteorologist Mike Wofford said. 

It could be even more in the mountains. Gusts could reach 60 to 80 mph (96.5 to 127.8 kph) in parts of the central coast.

A powerful storm is turning roads into rivers while triggering torrential mudslides as apocalyptic scenes sweep southern California on Christmas Eve. (Pictured: A view of a flooded street close to the Meta Campus during the downpour in Menlo Park, CA, on December 24) 

Storms began to move in late Tuesday evening and were expected to intensify throughout Christmas Eve, while a ‘clipper’ weather system is due to submerge much of the West Coast and Midwest in rain and snow on Christmas Day. (Pictured: Menlo Park, CA, on December 24)

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.