The biggest storm of the winter walloped Southern California on Thursday, but by Friday morning conditions were improving as the storm subsided.

Flooding, mudslides and debris flows caused by the heaviest rain in Los Angeles and southern California in a year shut Pacific Coast Highway from approximately Santa Monica to the Malibu Pier.

An atmospheric river is expected to bring torrential rain to California this week, threatening parts of the state with flash floods and mudslides.

The Pacific Coast Highway along Malibu canyon was closed after runoff pushed mud and debris over the road and into the Pacific Ocean (Video Credit: @PIOErikScott).

Three days of drenching rain, flooding and mudslides have forced evacuations and road closures, including a portion of the Pacific Coast Highway from Malibu and Pacific Palisades. The Pacific Palisades neighborhood of Los Angeles,

As heavy rain from a large storm subsided, officials in Southern California said rock and mudslides remain a threat.

On Friday, the storied coastal road had dissolved into a river of mud and debris after a powerful rainstorm sent those burned hillsides careening toward the ocean, turning canyons into rivers of mud and rocks.

Debris flows brought on by the strongest atmospheric river of the season swept a car off a southern California highway and into the ocean and left roads submerged in sludge