Californians brace for flooding in areas torched by wildfires

Ahead of the storm’s arrival, officials distributed sandbags, prepositioned rescue swimmers and told residents to have their go-bags ready.

Pedestrians cross a snowy street in downtown Kansas City, US as a winter storm passed through the area (Charlie Riedel/AP)

Rain has begun falling in California where an “atmospheric river” is expected to bring heavy downpours, winds and flooding to areas ravaged by wildfires.

Ahead of the storm’s arrival on Thursday, officials distributed sandbags, prepositioned rescue swimmers and told residents to have their go-bags ready.

Meanwhile, Portland coated its streets with 2,000 gallons of liquid anti-icer while officials in Oregon and Idaho opened emergency shelters to prepare for a punishing mix of snow and ice.

Winter Weather — A person walks along Kelly Drive and Water Works Drive after an overnight snow fall in Philadelphia, US (Alejandro A Alvarez/AP)

Southern California could see as much as six inches (about 15 centimetres) of rain in the mountains and three inches (about 7.6 centimetres) in coastal areas and valleys, according to Brent Bower, a hydrologist with the National Weather Service.

Strong wind gusts could bring down trees, cause power outages and delay flights.

Evacuation warnings were issued in Mandeville Canyon and other areas ravaged by the Palisades Fire, the most destructive fire in Los Angeles city history, over concerns about potential debris flows during the upcoming storm.

There were also warnings for Trabuco Canyon and other areas near the burn scar for the Airport Fire.

All Malibu schools were closed on Thursday and the Knott’s Berry Farm amusement park shuttered because of the atmospheric river – a long band of water vapour that can transport moisture from the tropics to more northern areas.

Daniel Swain, a climate scientist for the University of California Agriculture and Natural Resources, said the area is in desperate need of rain — but this may come too hard and fast.

The result could be debris flows and flash flooding around wildfire burn areas.

These burned areas are more at risk to debris flows because vegetation that helps to keep soil anchored has been burned away and loose debris, including ash, soil and rocks, have been added, he said in a statement.

County officials said roads may be closed and urged residents to be prepared should a mandatory evacuation order become necessary.