Severe storms still battering California

About 90 percent of California's population — more than 34 million people and 10 percent of the US population — were under flood-watches Monday as another severe thunderstorm slammed the West Coast after a short reprieve from heavy rains last week.

The number of deaths related to the storms climbed from 12 to 14 on Monday, state officials said.

Forecasters warned that a new wave of thunderstorm is going to be more severe.

More than 37 million people were under wind alerts Monday in California, Nevada, Oregon, Washington, Utah, Arizona and Wyoming as hurricane-force wind gusts topping 74 mph hit some of the states.

"This will be a fairly substantial second wave," Daniel Swain, a climate scientist at the University of California at Los Angeles, said on a live YouTube video Monday morning. "What falls is going to fall quickly."

On Sunday evening, President Joe Biden declared a state of emergency for California. The declaration cleared the way for assistance from the Federal Emergency Management Agency to coordinate disaster relief efforts in the state.

The storms hitting California are caused by a barrage of atmospheric rivers, which are long, flowing regions of the atmosphere that transport water vapor through the sky.

When atmospheric rivers make landfall, they often release water vapor in the form of rain or snow.

While the atmospheric rivers will continue to pummel California through early this week, its most potent system was expected to arrive Monday, the National Weather Service said.

"This storm was as bad as a couple of the hurricanes I've been through. Never in my life [as] a Californian have I felt this kind of windstorm," Carley Gomez, a meteorologist at ABC10 in Sacramento tweeted on Sunday.

Rescuers ended the search for a 5-year-old boy who was swept away by floodwaters in central coastal California while the entire community of Montecito was ordered evacuated Monday as residents grappled with flooding and mudslides as the latest of powerful storms hit the state.

The evacuation order came on the fifth anniversary of a mudslide that killed 23 people and destroyed more than 100 homes in the coastal enclave of about 8,600 people.

Since Dec 26, San Francisco has received more than 10 inches (25 centimeters) of rain, while Mammoth Mountain, a popular ski area in the Eastern Sierra Nevada, got nearly 10 feet (3 meters) of snow, the National Weather Service said.

The storms won't be enough to officially end California's drought, but they have helped.

Swain expects a break in the rain after Jan 18.

"That is my best guess right now, which is good because it will give the rivers in Northern California, and now in Central California, a chance to come down," he said.

Agencies contributed to this story.