Downpour ... Motorists drive down a flooded street in Bakersfield, California. Picture: Casey Christie/AP Source: AP

News reports on Friday said a homeless man and a young boy were killed by falling trees in the state of Oregon.

Severe flooding, mudslides and high winds — some gusting up to 225km/h — wreaked havoc as the unusually powerful storm bore down the California coastline, buffeting Los Angeles and San Diego.

Landslide ... Mountainsides stripped bare by a bushfire last year sent a damaging debris flow into the Ventura County community of Camarillo Springs. Source: AP

High seas ... Waves crash on the shore at Rockaway Beach, Oregon. Picture: Bruce Ely/AP Source: AP

The Los Angeles Times said the storm trapped some residents inside their homes and cars, and led officials to issue mass evacuations of some areas, which also were hit by widespread power outages.

The National Weather Service said among southern California’s hardest hit areas were foothills denuded of vegetation after being scorched by wildfires over the past few years, and which now are particularly prone to mudslides.

Destroyed ... The inside of this home is covered with about 70cm of mud. Source: AP

The clean-up begins. Source: AP

“Flash flooding and debris flows will be a particular threat in and below the recently burned areas,” the National Weather Service said in a bulletin on Friday.

Watching the water ... A surfer on the Huntington Beach pier waits for the large waves to show themselves on Thursday morning. Picture: Michael Goulding/AP Source: AP

The inclement weather sweeping into the region was being carried on a current with the unlikely name “Pineapple Express” — an intense stream of moisture stretching from Hawaii to the US West Coast.

“It’s clearly the strongest storm to impact the West Coast in the last three years,” Todd Morris, a spokesman for the National Weather Service, told AFP.

You can’t usually kayak here ... Steve Derst uses a kayak to inspect the damage to the trailer park where he lives. Source: AP

Blizzard warnings were issued for mountainous areas, the first such alerts since 2008, with up to a metre of snow expected.

Aerial view ... A satellite image shows the storm over the west coast on December 12. Picture: AFP Source: AFP

Hundreds of flights were cancelled on Thursday at San Francisco International Airport, but Los Angeles International Airport on Friday reported no increase in major delays.

Flash flood watches and warnings were in place all along the western United States from the Pacific northwest to San Diego at the Golden State’s southernmost tip.

Storm damage ... Palm fronds torn from trees by a storm sweeping through southern California lie on the ground at Sunset Beach. Picture: Michael R. Blood/AP Source: AP