Some areas had received more rain in the storm than they did the entire year before, National Weather Service meteorologist Jamie Meier said, though experts said the moisture would do little to improve local water supplies.
By Friday morning, Long Beach Airport had received 2.76 inches of rain, compared to 2.1 inches over the previous 12 months, Meier said. Downtown Los Angeles had received 2.54 inches and Gibraltar Dam near Santa Barbara was drenched with 7.56 inches.
A flash flood warning was in effect early Friday in Los Angeles in areas around Griffith Park that were denuded by last year's wildfires.
"Residents and motorists in and below recently burned areas should be alert to heavy mud and debris flows, which may block roads," a National Weather Service advisory warned.
Higher up, Mountain High ski resort received 18 inches of snow, but was forced to close its slopes Thursday due to high winds. The resort said on its Web site it would reopen Friday.
The National Weather Service issued a winter storm warning for the Santa Barbara County mountains through 10 p.m. Friday. The snow level was expected to drop to between 2,000 and 3,000 feet Thursday night, and down to 1,500 feet during heavier showers or thunderstorms.
At least one waterspout from the Pacific made landfall Thursday night, the National Weather Service said. The tornado tore the roof off of a building at Naval Base Ventura County in Point Mugu, meteorologist Curt Kaplan said.
Vance Vasquez, a base spokesman, said debris was scattered across the runway and "a good portion" of the roof was torn from Hangar 351, which houses aircraft. There were no immediate reports of injuries.
The storm had forced the closure of Interstate 5 late Wednesday on each side of the Grapevine section of Tejon Pass, which soars to an elevation of more than 4,000 feet between the Los Angeles Basin and the San Joaquin Valley. Hundreds of trucks and cars were stuck along a 40-mile stretch of the major north-south artery but most had been guided out by Thursday morning, the California Highway Patrol said.
A roughly 40-mile stretch of the icy interstate stayed closed until Friday morning after overnight rains helped clear snow on the road, CHP Officer David Porter said.
In Orange County, crews placed safety barriers against several homes in fire-scarred Modjeska Canyon Thursday.
"The rain resulted in a few minor debris flows behind a few houses but as far as I know there was no structural damage," Capt. Mike Blawn of the Orange County Fire Authority said.
Authorities are concerned about another storm forecast to hit the area over the weekend. Forecasters are predicting 4-6 inches to hit south and southwest facing mountain slopes between Saturday night and Sunday morning.
Heavy rain and hail prompted the Santa Anita horse track in Arcadia to cancel races Thursday, the fourth time this month. Its synthetic track has had drainage problems.
The storm was not expected to improve local water supplies. One of the driest rain seasons on record left reservoirs so low last year that several cities called for voluntary water conservation
In areas previously denuded by fire, including Malibu and some Orange County canyons, residents remained braced for the possibility of having to evacuate, but no incidents were immediately reported early Friday, reports CBS News affiliate KCAL-TV.