Another atmospheric river is slamming the West Coast, bringing more flooding concerns to storm-battered California | CNN

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Storm-battered California communities are bracing for another round of likely flooding, mudslides, toppled trees and power outages as the latest in an unrelenting parade of atmospheric rivers hits the West Coast Monday, with Gov. Gavin Newsom warning officials “expect to to see the worst of it still in front of us.”

The storm is expected to bring another surge of hazardous heavy rain, mountain snow and damaging winds to California, where thousands are already without power and some have been ordered to evacuate or warned they could be asked to flee.

More than 34 million people were under flood watches across much of California Sunday night. And more than 30 million were under moderate risks for excessive rainfall, while 28 million across the west were under a wind alert.

In Sacramento County, evacuation orders were issued for the community of Wilton along the Cosumnes River, with officials warning that “flooding is imminent” and that residents should flee before roads become impassable. The same community was ordered to evacuate during last week’s storm, when exit routes flooded quickly, officials said.

El Dorado, Monterey, Santa Cruz and Santa Clara and Alameda counties have issued evacuation warnings or recommendations for some areas due to possible flooding and other safety risks, with forecasters warning of swelling rivers.

Damaging winds were expected across Northern California and into Nevada through Monday, spurring fears of more downed trees and widespread power outages. The National Weather service in Sacramento warned residents to expect wind gusts up to 45-65 mph.

Wind gusts topping 100 mph were already being reported across the region by early Monday morning, including a 132 mph gust near Oroville, California.

There were more than 100,000 homes and businesses across California without power Sunday night, according to PowerOutage.US – down from over 400,000 without electricity earlier in the day after high winds and rain swept into the area.

As the storms pummel California, Newsom on Sunday submitted a request to the White House for a Presidential Emergency Declaration to support storm response and recovery efforts.

“We are in the middle of a deadly barrage of winter storms – and California is using every resource at its disposal to protect lives and limit damage,” Newsom said in a statement. “We are taking the threat from these storms seriously, and want to make sure that Californians stay vigilant as more storms head our way.”

This storm is arriving on the heels of a powerful cyclone that flooded roads, toppled trees and knocked out power to much of California last week. Earlier, a New Year’s weekend storm system produced deadly flooding.

Twelve Californians have died from “storm-related impacts,” including flooding, since late December, according to Newsom’s office.

“Floods kill more individuals than any other natural disaster. We’ve already had more deaths in this flood storm since December 31 than we had in the last two fire seasons of the highest fire acreage burned in California,” said California Emergency Services Director Nancy Ward during a news conference Sunday.

“If you don’t have to be traveling during peak period in the storm, please don’t,” said state Secretary of Natural Resources Wade Crowfoot. “Be prepared for power outages and other interruptions. Have those flashlights, the candles, batteries, charge cell phones at the ready.”

Already, flooded roadways and toppled trees and power lines are making travel difficult, according to the California Highway Patrol. Images from around northern California over the weekend show downed trees crushing cars and homes.

“Just a foot of water and your car’s floating. Half a foot of water, you’re off your feet. Half foot of water, you’re losing control of your vehicle,” Newsom said. “We’re seeing people go around these detours because they don’t see any obstacles – they think everything is fine, and putting their lives at risk or putting first responders lives at risk.”

Two major bouts of rain are expected to impact the West Coast over the next few days. The concern is not just the rain, snow and wind, but that there will be not much of a break in between events for the water to recede.

“While some of the forecast rain totals are impressive alone, it is important to note that what really sets this event apart are the antecedent conditions,” the National Weather Service office in San Francisco said. “Multiple systems over the past week have saturated soil, increased flow in rivers and streams, and truly set the stage for this to become a high impact event.

Newsom said California is experiencing “weather whiplash,” going from intense drought conditions to now contending with its fifth atmospheric river.

“It’s just a few months ago we were talking about these heat domes and extreme heat,” Newsom said.

Much of the state has already seen 5 to 8 inches of rain over the last week. Additional rainfall totals of 2 to 4 inches are expected across the coasts and valleys, and even more in mountains and foothills through Tuesday.

Flooding and mudslides are among the biggest concerns – especially on soil that’s already been saturated by the barrage of storms, as well as sensitive areas recently scorched by wildfires.

Water from swelling rivers could also spill over and inundate communities.

The rainfall over the weekend brought renewed flood concerns for local streams, creeks, and rivers. The Colgan Creek, Berryessa Creek, Mark West Creek, Green Valley Creek and the Cosumnes River all have gauges that are currently above flood stage or expected to be in the next few days.

“The cumulative effect of successive heavy rainfall events will lead to additional instances of flooding. This includes rapid water rises, mudslides, and the potential for major river flooding,” the National Weather Service said.

State officials said Monday that crews, including from the California National Guard, are prepared to move out quickly in the event of mud flows, avalanches or flash floods.

The moisture is expected to sink southward Monday night, making flooding “increasing likely” over the southern California coastal ranges Tuesday, according to the weather service.

In addition to the heavy rainfall, another round of strong winds is expected to accompany the storm as it pushes inland.

“Valley areas will likely see gusts as high as 45-50 mph, with gusts greater than 60 mph possible in wind prone areas,” the weather service office in Reno said, adding that the Sierra ridge could receive peak gusts between 130-150 mph Monday.

While the main concerns in coastal communities will be widespread flooding, gusty winds and dangerous beach and marine conditions, residents at the higher elevations are being warned about heavy snow and strong winds.

As the storm pushes farther inland, localized areas could see more than 5 feet of snow along the Sierra crest west of Lake Tahoe, the weather service said.

The heavy snow, coupled with strong winds, will also lead to near whiteout conditions on roads.