A historic 'bomb cyclone' was drenching California on Sunday, forcing evacuations in areas hit by wildfires, and ushering in stay-at-home orders in other parts of the state.
The weather system was the strongest recorded since records began, beating the previous record, set in 1977.
A 'bomb cyclone' occurs when the barometric pressure drops quickly, falling 24 millibars in 24 hours or less. The standard surface pressure on Earth is 1013.2 millibars, and the lower the pressure drops within a cyclone, the more intense a storm it creates. The Portland office of the National Weather Service said the pressure fell as low as 942.5 mb, recorded by a buoy 300 nautical miles from Aberdeen, Washington state.
Power lines were downed, mudslides triggered and roads closed as the storm hit.
In Floriston, in the midst of heavy rain, a truck which collided with a bridge wall and caught fire, forcing one lane of the I-80 eastbound.
More than 168,000 people were without power in California on Sunday, along with nearly 172,000 in Washington state and more than 30,000 in Oregon, according to Poweroutage.us.
The worst outages were in northern California.
Utility company PG&E said as of 2:15pm PT more than 130,000 customers were without power in the Bay Area, including 50,576 in the North Bay, 43,556 on the Peninsula, 21,773 in the East Bay, 7,523 in the South Bay and 7,234 in San Francisco.
Rocks and vegetation cover Highway 70 following a landslide in the Dixie Fire zone on Sunday
Huge chunks of rock and mountains of earth were dislodged on Sunday in Plumas County, following the heavy rain
Caltrans maintenance supervisor Matt Martin walks by a landslide covering Highway 70 in the Dixie Fire zone on Sunday
Cars drive by a sign on Highway 101 on Sunday in Corte Madera, California. Up to 10 inches of rain are expected to fall along the west coast
Up to 10 inches of rain was expected to wash over the West Coast, said meteorologist Marc Chenard of the Weather Prediction Center at the National Weather Service.
'It's an atmospheric river already moving through northern California,' he added.
The weather whiplash follows the busiest wildfire season in California history and heightens threats of flash flooding.
Much of the region is in severe, extreme or exceptional drought, as classified by the U.S. Drought Monitor.
'Burn scars, that's the area where the water tends to run off quicker so that's where the biggest flash flood risks are,' Chenard said.
'Warnings are of life-threatening flash flooding in and around the burn scars.'
Heavy downpour on Sunday over the burn scars of the Dixie Fire and North Complex sparked serious alarm.
Multiple mudslides were already reported in some of the 570,000 acres blackened by the Dixie Fire in the rugged Sierra Nevada mountains northeast of San Francisco, the second-largest wildfire recorded in state history.
San Mateo, Santa Barbara and Santa Cruz counties all issued evacuation orders.
Workers try to divert water into drains as rain pours down in Marin City on Sunday
Frantic efforts were underway on Sunday to divert water into drains and prevent flooding in Marin City
Governor Gavin Newsom's office of emergency services said they were expecting mudslides.
'Resources have been deployed to these locations as flooding after fire is often more severe, as debris and ash left from the fire can form mudflows,' the OES said in a statement.
'As rainwater moves across charred ground it can also pick up soil and sediment & carry it in a fast-moving stream of floodwaters.'
Residents of San Mateo County who were not under evacuation orders were told to stay home.
Officials said they were inundated with requests for assistance.
'Our 9-1-1 dispatchers are fielding a large number of calls during this storm emergency,' they tweeted.
'You can help by following emergency officials' instructions. If you can stay put, do not travel today.'
Further north, the Sacramento office of the National Weather Service tweeted: 'Stay home if you can, and if not, make sure to drive with caution!'
Strong winds and high waves are pictured on Sunday in Depoe Bay, Oregon
Heavy waves break against the Oregon coast as a bomb cyclone storm system moves over the northwest on Sunday
Water flows down a street on Sunday in San Rafael, California, as the 'bomb cyclone' passes overhead
Workers in the Levi's Stadium in Santa Clara, California, push water off the tarp covering the field before an NFL football game between the San Francisco 49ers and the Indianapolis Colts
Winds over 50 miles per hour gusted through San Francisco.
Sandbags were being handed out and evacuation centers were opened in Sacramento.
The Sacramento Office of Emergency Service tweeted 'Remember - never drive through standing water! Turn around, don't drown!'
Snow was expected in higher elevations, Chenard said.
'It's a pretty impressive storm system,' Chenard said.
'It's happening now and it's going to continue into the day tomorrow. It will be gradually shifting southward across Central California tonight and tomorrow.'