California braces for worst as powerful storm set to bring heavy rain, potential mudslides

Authorities and residents in California were bracing for the worst on Thursday as forecasters warned that major problems could still be on the way from a dangerous Pacific storm.

Record rain fell Wednesday in parts of Southern California, where thousands left their homes over fears of mudslides and debris flows.

Although nothing disastrous occurred, forecasters warned that the potential for disaster was still very possible as rain was set to pick up.

Workers place sandbags on a washed-out driveway on La Tuna Canyon Road in Sun Valley, Calif.

Workers place sandbags on a washed-out driveway on La Tuna Canyon Road in Sun Valley, Calif. (Hans Gutknecht/Los Angeles Daily News via AP)

"We're very concerned," National Weather Service meteorologist Joe Sirad said. “We're hoping this isn't a cry-wolf scenario where people will pooh-pooh what we're saying.”

A long plume of subtropical moisture, known as an atmosphere river, came ashore on the central coast and spread as far south as Los Angeles and as far north as the San Francisco Bay Area.

The storm moved eastward, bringing the threat of flooding to the San Joaquin Valley and Sierra Nevada, where winter storm warnings for fresh snow were in effect on the second day of spring.

As nearly 5 inches of rain fell in some parts of the state, authorities were keeping close watch on Santa Barbara County -- hoping there wouldn’t be a repeat of January’s mudslides that killed 21 people in Montecito. A similar atmospheric river was the cause of those storms.

A UCLA climate scientist wrote in a blog that this storm could be the year’s strongest and may bring more rain than January's storm did.

This March 21, 2018 satellite image provided by the National Oceanic and Atmospheric Administration shows a strong Pacific storm, known as a "Pineapple Express," the lower arc of clouds that range from Hawaii at lower left, aimed directly at California, middle right, that dropped heavy rain on a wide swath of the state.

This March 21, 2018 satellite image provided by the National Oceanic and Atmospheric Administration shows a strong Pacific storm, known as a "Pineapple Express," the lower arc of clouds that range from Hawaii at lower left, aimed directly at California, middle right, that dropped heavy rain on a wide swath of the state. (National Oceanic and Atmospheric Administration via AP)

Mud and rockslides closed several roads in the region, including Highway 1 at Ragged Point near Big Sur, not far from where the scenic coast route is still blocked by a massive landslide triggered by a storm last year.

A large pine tree was felled in Los Angeles, landing across a residential street into a picket fence. No one was hurt.

Santa Barbara County had already ordered the evacuation of areas along its south coast near areas burned by wildfires dating back to 2016.

“We're hoping this isn't a cry-wolf scenario where people will pooh-pooh what we're saying."

— Meteorologist Joe Sirad

"We actually do feel good about the evacuation order," Grimmesey said. "Law enforcement was out in the extreme risk areas of Montecito yesterday knocking on doors. For those that were home, we had a very good cooperation rate with people leaving."

Many residents in Santa Barbara and Ventura counties have faced repeated evacuations or advisories since December, when a wind-driven fire grew into the largest in recorded state history and destroyed more than 1,000 buildings.

In Los Angeles County, authorities canceled some planned mandatory evacuations because of a projected decrease in rainfall but kept others in place because of debris flows in one canyon area stripped bare by wildfire.

The Associated Press contributed to this report.