California hit by widespread flooding, power outages amid back-to-back storms

The second of back-to-back atmospheric rivers battered California on Sunday, flooding roadways and knocking out power to more than 845,000 people and prompting a rare warning for hurricane-force winds as the state braced for what could be days of heavy rains.

Atmospheric rivers are storms akin to rivers in the sky that dump massive amounts of rain and can cause flooding, trigger mudslides and result in loss of life and enormous property damage.

Sunday's storm inundated streets and brought down trees and electrical lines across the San Francisco Bay Area, where winds topped 96 km/h in some areas. Gusts exceeding 128 km/hwere recorded in the mountains.

Just to the south in San Jose, Calif., emergency crews pulled occupants out of the windows of a car stranded by floodwaters and rescued people from a homeless encampment alongside a rising river.

In Southern California, officials warned of potentially devastating flooding and ordered evacuations for canyons that burned in recent wildfires that are at high risk for mud and debris flows. The U.S. National Weather Service office for Los Angeles warned that "all systems are go for one of the most dramatic weather days in recent memory."

Nearly 846,000 customers were without electricity statewide by Sunday evening, with most of the outages concentrated in coastal regions, according to poweroutage.us.

Six San Francisco Bay Area counties were at low risk of waterspouts coming ashore and becoming tornadoes, said the Storm Prediction Center. The last time the centre forecasted a tornado risk in the region was in February 2015, according to the San Francisco Chronicle.

Winds caused hours-long delays at San Francisco International Airport. By 2:30 p.m. Sunday, 155 departing flights were delayed and 69 had been cancelled, according to the tracking website FlightAware.

Much of the state had been drying out from the system that blew in last week, causing flooding and dumping welcome snow in mountains. The latest storm, also called a "Pineapple Express" because its plume of moisture stretches back across the Pacific to near Hawaii, arrived offshore in Northern California on Saturday, when most of the state was under some sort of wind, surf or flood watch.

The weather service on Sunday issued a rare "hurricane force wind warning" for the Central Coast, with wind gusts of up to 148 km/h possible from the Monterey Peninsula to the northern section of San Luis Obispo County.

Meanwhile, Southern California was at risk of substantial flooding beginning late Sunday because of how slow the system was moving, said Ryan Kittell, a meteorologist at the weather service's Los Angeles-area office.

"The core of the low pressure system is very deep, and it's moving very slowly and it's very close to us. And that's why we have those very strong winds. And the slow nature of it is really giving us the highest rainfall totals and the flooding risk," he said at a Sunday briefing.

Evacuation orders and warnings were in effect for mountain and canyon areas of Monterey, Santa Barbara, Ventura and Los Angeles counties. LA County Supervisor Lindsay Horvath urged residents near wildfire burn areas of Topanga and Soledad canyons to heed orders to get out ahead of possible mudslides.The county set up shelters where evacuees could spend the night.

Gov. Gavin Newsom on Sunday declared a state of emergency for Los Angeles, Orange, Riverside, San Bernardino, San Diego, San Luis Obispo, Santa Barbara and Ventura counties. The Governor's Office of Emergency Services activated its operations center and positioned personnel and equipment in areas most at risk.

The storm was expected to move down the coast and bring heavy rain, possible flash-flooding and mountain snow to the Los Angeles area late Sunday, before moving on to hammer Orange and San Diego counties on Monday.

The weather service forecast up to 20 cmof rainfall across Southern California's coastal and valley areas, with 35 cmpossible in the foothills and mountains. Heavy to moderate rain is expected in Southern California until Tuesday.