California storm updates: State of emergency in effect as flooding, mudslides hit Southern California

An atmospheric river is bringing historic rainfall to Southern California.

A second storm within one week is pummeling California with heavy rain and life-threatening flooding.

Gov. Gavin Newsom has issued a state of emergency for counties including Los Angeles, Santa Barbara and Ventura, where floodwaters and mudslides have swept through roadways.

Latest headlines:

LA reports 475 total mudslides since storms began

Los Angeles officials said Tuesday night there had been 475 mudslides since the storms brought rain to the area over the weekend. Thirty-eight buildings now need inspection due to mudslides and slope failures. So far, four buildings have been given no-entry red tags and nine are yellow tagged, which means people can only go into to collect their possessions. The city has also, at its most recent count, a record of 390 fallen trees and branches and 441 potholes. Authorities also said they've cleared 963 catch basis and stormwater conveyance systems.

-ABC News' Marilyn Heck

Latest forecast

The heaviest rain is moving south of Los Angeles, toward San Diego, on Tuesday afternoon. By Tuesday night, the heavy rain will reach Arizona.

Flood watches will remain in effect through Tuesday night across Southern California, from Los Angeles to San Diego, as well as in parts of Nevada and Arizona.

A tornado warning has also been issued in the San Diego area.

Through Thursday, an additional 1 to 2 inches of rain is possible in parts of Southern California. With the ground already so saturated, mudslides and flash flooding will remain a threat for much of the week.

-ABC News’ Melissa Griffin

Los Angeles mayor: 'This storm continues … take precautions'

"This storm continues -- and that means we still need Angelenos to take precautions," Los Angeles Mayor Karen Bass warned Tuesday.

Periods of rain will continue Tuesday creating dangerous conditions on the roads and increasing the chance of mudslides and flooding, Los Angeles Fire Department Chief Kristin Crowley said.

No fatalities have been reported in LA, Bass said.

Crews have responded to 307 mudslides and 257 fallen trees, Crowley said.

If you must go outside, use caution, Crowley warned. Slow down if driving and always be on the lookout for downed power lines and trees, she said.

The mayor commended residents who have checked on each other in hard-hit communities and stressed that everyone should check on their neighbors.

The "historic" rain is expected to taper off late Tuesday night, National Weather Service meteorologist Ariel Cohen said.

There’s a chance for more atmospheric rivers this spring, Cohen said.

By the numbers

Downtown Los Angeles recorded 7.03 inches of rain on Sunday and Monday, marking the wettest two days in the city since 1956.

Los Angeles averages 14.25 inches of rain for an entire year. So far this year, LA has recorded nearly 11 inches of rain, or 75% of the city's annual rainfall.

And the rain is still falling. As of Tuesday morning, the three-day rainfall totals have climbed to: 12.2 inches in San Bernardino County; 12 inches in Bel Air in Los Angeles County; 9.4 inches in Santa Barbara County; 8.7 inches in Ventura County and 7.6 inches in downtown Los Angeles.