In Los Angeles, heavy rains downed power lines hitting a auto and then electrocuting a man who later died in the hospital. More than 300 flights were delayed or canceled Friday at Los Angeles International Airport.
Major interstates were flooded and a sinkhole in Studio City, near Los Angeles, swallowed two cars as TV crews filmed the incident.
"This storm could have a significant impact across Southern California, causing damage and flash floods", said Dan Gregoria, a forecaster with the National Weather Service.
National Weather Service said the storms carried a threat of flooding, mudslides and risky travel.
The storm is expected to be the strongest in years.
One person drowned in his auto due to sudden flash flooding.
Total rainfall predictions ranged from 2 inches to 6 inches on the coast and from 5 inches to 10 inches in foothills and coastal mountains.
They were discovered when a fire service helicopter tried to rescue those gripping to their cars for safety as their vehicles were washed down one of the town's flooded streets.
Downed trees and power lines are viewed near a school in downtown Los Angeles, Feb. 17, 2017.
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Lights rains along the Central Coast and Northern California are expected to intensify Sunday afternoon and last through the beginning of the week as a warm front moves across the region with possible 45-mile-per-hour wind gusts, NWS meteorologist Roger Goss said. The heavy rain and melting snowpack threatened to undermine a spillway at one of the largest dams in the country, which prompted the evacuation of 188,000 residents earlier this week. The area received about 3 inches of rain as of Saturday morning.
In southwest California, the National Weather Service warned the area will see the strongest storm to hit this season. "The last storm we had it started coming in the garage, so this time I am just going to stop it before it happens", said Josh Jones of Oxnard.
Winds gusting to 70 miles per hour or more lashed parts of the region.
Meanwhile, Amtrak suspended service Saturday morning between Los Angeles and San Luis Obispo because of mudslides in the Santa Barbara area, officials said.
On Saturday, searchers found the body of a man in his 20s who was swept down a rain-swollen gully in Thousand Oaks a day earlier.
A flash flood watch for Los Angeles, Ventura and Santa Barbara counties was canceled Saturday morning.
The city of Duarte, located near the San Gabriel Mountains east of Los Angeles, ordered 180 homes to evacuate today ahead of the storm, and voluntary evacuation orders were issued for Camarillo Springs, reported the Weather Channel. A record 1.96 inches fell at Long Beach Airport, breaking the daily rainfall record of 1.81 inches set in 1980.
These storms will continue to test the limits of California's water infrastructure, UCLA climate scientist Daniel Swain said.
In addition to crippling air travel, the several inches of rain expected could lead to risky flash flooding in some places as well as mud and rockslides capable of shutting down roadways.