A trio of storms bringing relentless downpours and heavy snow have sparked warnings for "impossible" travel conditions as the US battles a "deadly weather onslaught".
An anticyclone "bubble" smothering the United States has allowed three major storm systems to stir chaos across western and southern states.
Historic California rainfall has been driven by a powerful "atmospheric river" of moisture, with severe weather reported to have killed three people.
Relentless downpours this week sparked an avalanche in Lee Canyon, Nevada, while hundreds of thousands of homes have been left without power.
California has been hit hard by storms and floods
The Weather Channel
Heavy rain is expected to persist over the coming days while heavy snow across Nevada, Utah, Colorado, Arizona and New Mexico has triggered a raft of National Weather Service (NOAA) winter storm warnings.
Winter storms hitting southern regions with up to three feet of snow could render travel routes impassable, according to the NOAA.
A spokesperson said: “Travel could be very difficult to impossible Residents may be stranded due to closed roads.
“If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency.
“A continued influx of moisture from the Pacific … will bring heavy snowfall to regional mountain ranges of the Intermountain West over the next couple of days.”
Southern California will continue to be hit by floods as an atmospheric river storm system dumps inches of rain across the regions.
The huge channels of water high in the atmosphere can carry up to a tonne of rain, dumping it over western states as they plough in from the Pacific.
Heavy rain is expected to persist
The Weather Channel
Unstable atmospheric conditions will also bring the risk of thunderstorms through the week, according to national weather advisors.
Plunging temperatures further inland will bring the added risk of freezing rain, triggering ice warnings in parts.
Coastal flood warnings remain in place across southern California while strong winds threaten Arizona and New Mexico.
California storms have left three people dead from falling trees as "rivers of mud" gushed through the state.
Heavy rain leaving ground saturated will bring an ongoing risk of landslides through the week, according to The Weather Channel.
A spokesman said: “Over the weekend, a bubble of high pressure aloft camped over the Midwest and clogged up the weather pattern.
“That allowed three separate storm systems to linger and have significant impacts.
The southwest will also be affected
National Weather Service (NOAA)
“At least three people were killed by falling trees in California, and rivers of mud rushed through streets in the Los Angeles area.”
Weather channel meteorologist Domenica Davis said: “Southern California is reeling from a deadly weather onslaught with an atmospheric river storm system dumping historic amounts of rainfall and killing at least three people.
“The storm enhanced by a ‘pineapple express’ brought powerful winds with gusts of up to 60 miles per hour.
“While there is some more heavy rain to come, the storm will soon begin to move eastwards, and out of southern California.”
Volatile weather conditions are being driven by tussling airmasses over the US.
Warm air from the south is meeting cold air to the north left from the recent winter blast, triggering heavy downpours and thunder.
Jim Dale, US weather correspondent and meteorologist for British Weather Services, said: “Warm and humid air coming out of the Gulf of Mexico is brining unstable atmospheric conditions, and with the very heavy rain there will be the risk of thunderstorms and strong winds in parts.”