California is bracing for a fresh lashing of rain and snow as a cyclone in the Pacific Ocean is expected to steer significant amounts of moisture toward the West Coast on Wednesday and Thursday.
In its latest forecast, the National Weather Service (NWS) said that a "robust plume" of moisture will move along the West Coast and into southern California overnight on Wednesday, bringing heavy rain across the state.
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.
Maps produced by the NWS of projected new precipitation show that, as of 6 p.m. ET on Thursday, nearly four inches of rain may fall near Eureka, with between one and three inches for other coastal regions of northern California.
Rainfall is expected to intensify across the region and into southern Oregon by midday on Friday, with over four inches near Eureka and Medford, and around four inches in neighboring areas.
The region is unlikely to see any let-up, as meteorologists are predicting that 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 two inches of rain could fall in the region on Wednesday and Thursday, with up to five inches in mountain regions. Wind gusts are expected to reach up to 50 miles an hour and up to two feet of snow is anticipated in higher elevations.
Meanwhile, meteorologists in Sacramento noted that a swathe of California, from Eureka to San Francisco, had been placed under a flood watch. The NWS station there said that up to three inches of rain could fall in valleys—with the heaviest around Sacramento—and in the foothills. The heaviest rain was expected north of the I-80.
Maps based on satellite modeling by WXCharts shows a thick band of rain arching across California through Thursday, before another plume curls up the West Coast from Sunday into Monday.
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 is able to 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 Climate Prediction Center said that there was a more than 60 percent chance of "hazardous, heavy" precipitation across southern California and into the desert Southwest as another atmospheric river storm breaks.
There is also a moderate chance of high winds in coastal areas, bringing the possibility of coastal erosion and "persistently high waves," it said.
Uncommon Knowledge
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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
