At least one person has died in Redding, California, because of the torrential rain and significant flooding as the state braces for worsening conditions this week.
Redding Mayor Mike Littau confirmed the death in a Facebook update Sunday night.
Littau provided more details about the death Monday on Facebook, saying the cause of death remains under investigation.
"The call came into 911 from a person stuck while water was coming into the vehicle," Littau wrote, adding that the caller's phone then died.
"Redding Police Officer swam out into the water, broke the windows and pulled victim to shore," he said. "CPR was done but the person did not live."
An evacuation center is open in Redding, according to the city's Facebook page.
Displaced community members can go to Pilgrim Congregational Church to "get warm, stay dry, and access snacks and warm drinks."
A striking video recorded Sunday in Redding shows roadways submerged by flash flooding and what appears to be a water main break, causing a massive plume of water to erupt from the ground.
Flood watches remained in effect Monday afternoon for 41 million people, encompassing nearly all of California and parts of southern Nevada and northwest Arizona.
Cities at risk include San Francisco, Los Angeles and San Diego.
A potent atmospheric river is fueling the flooding and will continue throughout the week, with the moisture plume beginning to move toward Southern California.
San Francisco's watch is expected to run from Monday morning through late Thursday, Los Angeles' from Tuesday afternoon to late Wednesday and San Diego's from early Wednesday through Thursday.
More rain, wind and snow will slam the West from Tuesday through Friday, most likely increasing the flood threat.
Redding "is very concerned" that the rain Tuesday to Friday could have a bigger impact than what the city already experienced Sunday, Littau said.
"Departments are working to repair damage from Sunday evening and to stage resources for the next storm system expected to arrive on Tuesday," according to the Redding Facebook page.
On Monday afternoon, Littau advised residents to "stay off the roads" and to "be aware of surroundings."
In a statement Monday, Los Angeles Mayor Karen Bass advised residents who have holiday travel plans this week to "use caution on the roads, plan ahead, and stay informed."
Bass also encouraged residents to sign up for emergency alerts at NotifyLA.org.
On Monday, bands of moisture will target north-central California into the northern Sierra, which can expect 2 to 4 inches of rain. Higher elevations will be hit with heavy mountain snow and strong winds, creating dangerous travel conditions.
Torrential rain will pass over the Northern California coastline on Tuesday before it moves into parts of Southern California.
By Christmas Eve, treacherous travel conditions are forecast across California, with the heaviest rain in the southern part of the state from Santa Barbara to Oceanside.
