30,000 told to leave Californian communities previously hit by mudslides and fires

Rusty walks among debris in northern Limestone County, near Ardmore, Alabama, after a violent storm swept through the area. Photo / AP

Authorities ordered tens of thousands of people to flee their homes as a powerful storm headed towards California, where many communities face the threat of flooding and destructive debris flows from areas burned bare by huge bushfires.

An atmospheric river — a huge plume of subtropical moisture — took aim at the state's central and southern coast, where the wealthy community of Montecito near Santa Barbara is still trying to recover from a January storm that unleashed mudslides from a vast burn area, swamping homes and killing 21 people.

The storm was expected to arrive today and last until Friday, bringing 5 to 13 cm of rain to coastal areas and valleys, and 13 to 25cm in foothills and mountains, the National Weather Service said.

The California threat comes as storms have left a trail of damage across the US South.

Authorities told as many as 30,000 people to leave communities on the south coast of Santa Barbara County, where mudslides from a January 9 deluge destroyed or damaged hundreds of homes in Montecito, killed 21 people and left two children missing.

Authorities also ordered evacuations in parts of neighbouring Ventura County.Many residents of both counties have faced repeated evacuations or advisories since December, when a wind-driven fire grew into the largest in recorded state history.

It scorched more than 1,140 sq km, destroyed 1063 buildings and damaged 280 others.

The National Weather Service said forecasting models of the atmospheric river indicated the first 24 to 36 hours of the storm would target southern Santa Barbara County, western Ventura County and farther up the coast in San Luis Obispo County.

With violent weather ploughing through the US Southeast, the kitchen windows exploded at Richard Brasher's home in eastern Alabama.

Using couch cushions for protection, Brasher hid in the bathtub with his wife, daughter and two grandchildren as the storm passed near Jacksonville State University. The roar was terrifying, Brasher said: "I thought we were gone," he said.

Officials suspected a tornado was to blame for the damage there. With electrical transformers exploding and trees crashing down all around, Brasher, 60, said it felt like wind "picked up and shook the whole house."

"We were scared to death. It blew the paint off my house," he said.

The storm had threatened millions of people across the Deep South, prompting tornado warnings yesterday in Mississippi, Alabama and Georgia.

The area around Jacksonville State University in Alabama was among the hardest hit and thousands of buildings and vehicles were battered by large hail after the night of violent weather.

Several shelters opened, schools were closed, trees and power lines were down today. Jacksonville State advised people to avoid traveling near campus. Most students were away for spring break.

Mark Tenney helps in the clean-up of his neighbour Bob Walters' house in Ardmore, Alabama. Photo / AP

Part of the roof was ripped off the nursing school and Pete Mathews Coliseum, a 3500-seat basketball arena. Pieces of lumber and bent metal covered the ground along with insulation that looked like yellow cotton candy.

In Georgia, at least two communities suffered widespread damage to homes.

In one neighbourhood near Atlanta, "it looks like someone did a bombing run down the street," Georgia's insurance commissioner, Ralph Hudgens, said after touring the scene.

Multiple homes were destroyed in the subdivision southwest of Atlanta, he said.

The same storm system that battered Alabama and Georgia was taking aim at a large part of Florida and coastal communities in Georgia and the Carolinas.

Much of north Florida and the entire Georgia and South Carolina coasts would be at an "enhanced" risk for severe storms, which could include damaging winds, large hail and a few tornadoes, the National Storm Prediction Centre said.

The area most at risk is heavily populated, with more than 10 million people and major Florida cities such as Jacksonville, Tampa and Orlando, Savannah, Georgia; and Charleston, South Carolina.

- AP