California faces another atmospheric river as severe weather hits US

'It's all part of the same system,' a National Weather Service meteorologist says

The US on Wednesday continued to see extreme weather patterns, including tornadoes, snow and torrential rains.

Ferocious winds and soaking rain from the Pacific is sweeping towards California, ushering in another day of floods, mudslides and potential blackouts across the state.

Heavy rain will start falling across Northern California on Wednesday and strong winds will begin raking the region by midday, said Hannah Chandler-Cooley, a National Weather Service meteorologist in Sacramento. The Sierra Nevada mountains could receive about a metre of snow through Thursday.

“It is a pretty strong system for most of Northern California,” Ms Chandler-Cooley said.

California is set for more destructive weather in the coming days after enduring a battering last week when a similar system — called an atmospheric river — came ashore, causing widespread flooding and killing at least one person. While destructive in some parts of the state, the deluge helped California pull itself out of a years-long drought.

“These little breaks will be few and far between, there is not going to be much recovery time between these atmospheric rivers,” Andrew Orrison, a forecaster at the US Weather Prediction Centre, said on Wednesday.

“These additional events are going to pile up and exacerbate the situation out there.”

The latest storm will spread southward across the state, adding to heavy rain across Los Angeles. As much as 10cm of rain could fall, with up to double that amount in some isolated mountainous areas, according to the weather service.

Elsewhere, a wintry blast that hit the Northern Plains and the Upper Great Lakes is expected to spread into New England by Wednesday.

It was part of a larger weather front bringing heavy showers, severe thunderstorms, hail and tornadoes to the lower Mississippi Valley, Gulf Coast, Tennessee Valley and southern Appalachians.

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Tornado watches and severe thunderstorm warnings were in effect across much of Louisiana, Mississippi, Alabama and Georgia, along with flood watches posted along the southern fringe of that zone.

The National Weather Service tallied eight tornado reports as of Tuesday night, plus dozens of instances of high winds causing damage to trees, power lines and homes.

“It's all part of the same system. The heavy snowfall is occurring on the west to northern side of the storm … and then the rainfall and severe weather is across the south,” meteorologist Allison Santorelli said.

News agencies contributed to this report