Maps show that parts of California will receive more than two inches of rain in the coming day, as the first of two atmospheric river storms tips heavy precipitation over Western states.
In its latest forecast, the National Weather Service (NWS) said that a "plume of moisture" will aim towards southern California, producing heavy rain before moving into the southern Plains by Saturday.
Localized areas of flash flooding are expected, while mountain regions further inland are predicted to see more heavy snowfall after successive bouts so far this winter.
In many areas of California, there is a more than 90 percent chance of rain until midnight on Friday, with regions to the north of Los Angeles having a near-certain probability of experiencing rain. On the California-Nevada border, there is a hundred percent chance of rain.
Los Angeles and the surrounding areas are forecast to see around two inches of rain by 6 a.m. ET on Friday, while about an inch of new precipitation is predicted across the Sierra Nevada range, the NWS maps show. The rest of California will see rain and snow, though in lower amounts.
While the NWS said that the threat of excessive rainfall over California would end on Friday, the region is unlikely to see much let-up, as meteorologists are predicting light rain to continue before another, potentially stronger atmospheric river storm will make landfall next week, between February 4 and 8, bringing at least a 70 percent chance of precipitation to California and the Southwest.
Western states have already faced several bouts of snowfall so far this winter, having been subjected to a "prolific series" of atmospheric river storms from the Pacific.
Around the same time last year, California was battered by a series of deadly storms that brought severe flooding. Thousands of homes were left without power and many people were evacuated.
The NWS station in Los Angeles warned residents that up to three inches of rain could fall in the region through Thursday, with up to five inches in mountain regions. Wind gusts are expected to reach up to 55 miles an hour and up to 18 inches of snow is anticipated in higher elevations.
Meanwhile, meteorologists in Sacramento noted that "slick roads from rain are already being observed" across northern California, cautioning motorists to take extra care while driving.
Atmospheric rivers are narrow channels in the atmosphere that are able to 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.
California naturally has an atmospheric river flowing towards it that travels from the subtropics, known colloquially as the Pineapple Express.
The NWS's long-range outlook suggests that a swathe of western states is expected to see above-average precipitation between February 6-10, with southern California and southwestern Arizona having the highest likelihood of rain over normal totals.
Uncommon Knowledge
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
About the writer
Aleks Phillips is a Newsweek U.S. News Reporter based in London. His focus is on U.S. politics and the environment. ... Read more
