Winter storm warnings are in place for parts of eight states as a powerful atmospheric river storm from the Pacific Ocean moves east after making landfall in California on Sunday.
The National Weather Service (NWS) issued alerts for Alaska, Arizona, California, Colorado, Idaho, Nevada, Utah and Wyoming, warning of heavy snow, high winds and the continued threat of flooding.
It comes after the storm system brought heavy rain and areas of flash flooding to California, which caused mudslides and saw trapped residents clinging to trees.
The state already faced several inches of rainfall last week after a "plume of moisture" from the subtropics made its way eastward on Thursday and Friday. The NWS station in Los Angeles warned the following storm would make "life-threatening and damage flooding" possible.
The flooding prompted California Governor Gavin Newsom to declare a state of emergency for several counties in Southern California on Sunday.
Around the same time last year, California was battered by a parade of deadly storms that brought severe flooding. Thousands of homes were left without power and many people were evacuated.
In its latest forecast, the NWS said the threat of heavy rain and flash flooding would expand into the desert southwest on Tuesday, while showers and thunderstorms would continue to linger over southern California. It cautioned that "the risk for flooding and mud/debris flows remains given the very wet antecedent conditions" in the region.
As the storm moves eastward, heavy mountain snow is expected, with "particularly high" snow totals in some places. Snowfall in excess of two feet is anticipated for the Four Corners region, while up to a foot is expected in the Great Basin and northern Rockies.
Up to 23 inches of snow in higher elevation regions of Arizona, though snow will mix with rain in some areas. Wind gusts of up to 50 miles an hour which could bring down tree branches and cause power outages are expected.
As much as 18 inches of snow could fall in parts of Nevada, with winds as high as 45 miles an hour in places.
In eastern Colorado, up to three feet of snow is expected in mountain areas above 10,000 feet—with smaller amounts at lower elevations—while wind gusts reach 55 miles an hour. Two feet of snow is predicted for the Southern Mountains of Utah, with locally higher amounts possible.
Portions of northwestern Wyoming will also be impacted by the storm, where up to two feet of snow could accumulate.
This continues into eastern central Idaho, where as much as 18 inches of snow is expected, making driving conditions "very difficult to impossible."
Atmospheric rivers are narrow channels in the atmosphere that can carry a large amount of moisture with them. They form when cold air from the Arctic meets warm, moist air from the tropics, cooling it to form heavy precipitation.
According to the National Oceanic and Atmospheric Administration, a strong river can transport as much as 15 times the amount of water flowing through the mouth of the Mississippi River.
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Aleks Phillips is a Newsweek U.S. News Reporter based in London. His focus is on U.S. politics and the environment. ... Read more
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