After basking in dry, mild weather for several weeks, the tide is turning for California, with an onslaught of rain, snow and wind expected over Christmas week as a series of atmospheric rivers unleash a firehose of moisture on the Golden State.
"Anyone with holiday travel plans by road and by air should keep an eye on the forecast and adjust accordingly," theNational Weather Service advised in an online forecast.
How much rain? As much as 10 to 15 inches along the California coast, including the Monterey Bay to San Francisco Bay areas, saidWeather Trader meteorologist Ryan Mauein an email to USA TODAY.
"The firehose is turned on and will not turn off anytime soon," said meteorologist Matt Lanza on his blog "The Eyewall."
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Train of storms
"The train of storms, including a Pineapple Express that has focused on western Washington, will shift southward this weekend to concentrate on California through much of the week of Christmas,"said Alex Sosnowski, AccuWeather senior meteorologist, in an online forecast.
The Pineapple Express is the nickname for a specific type of atmospheric river, which has its source in the tropics near Hawaii.
"As the rounds of rain intensify, so will the risk of flooding and mudslides," Sosnowski said.
The weather service saidthat "onshore flow will continue to direct atmospheric rivers towards the West Coast, causing heavy precipitation to California in particular."
Weekend washout
An atmospheric river is forecast to take aim at northern California over the weekend, bringing heavy precipitation with some high rain rates, theweather service said.
"The storm from Saturday night Dec. 20 to Monday Dec. 22 will bring more substantial rain to northern California,"AccuWeather lead storm warning meteorologist Michael Stahlman said.
There is the potential for several inches of rain to fall in a few hours at the height of the atmospheric river from Sunday Dec. 21 to Monday Dec. 22 in the west-facing slopes of the coast ranges, Siskiyous and northern Sierra Nevada, AccuWeather said.
The weather service in San Franciscosaid the system will bring moderate to heavy rainfall to the Bay Area and Central Coast from Saturday evening Dec. 20 through Tuesday evening Dec. 23.
"Isolated to scattered flash floods are possible in low-lying and urban areas. Some small creeks and streams will likely flood," the weather service said.
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SoCal soaking
It is possible that rain begins in parts of coastal Southern California as early as Tuesday Dec. 23,AccuWeathersaid.
"Drenching downpours and urban flooding problems are predicted to occur in the Los Angeles and San Diego metro areas from Wednesday Dec. 24 to Friday Dec. 26, which may spoil outdoor Christmas-related activities," AccuWeather's Sosnowski said.
The weather service in Los Angeles said "a strong storm will bring many inches of rain to the entire area Tuesday Dec. 22 through Wednesday Dec. 24. It is likely that 1 to 2 inches of rain will fall across the coasts and valleys and 2 to 4 inches across the foothills and mountains."
Sierra Nevada snow upcoming
Snow levels will start off high this weekend but will fluctuate in the Sierra Nevada through the week of Christmas, AccuWeather said. "Several feet of snow are expected on the ridges and peaks of the Sierra Nevada, which will be a boon for ski enthusiasts over the holidays and a future boost for runoff during the spring and early summer, as little to no snow has fallen thus far this season," Sosnowski said.
Theweather service in Renosaid that "colder winter storms are possible around Christmas Day, which might lead to holiday travel disruptions in and across the Sierra."
This article originally appeared on USA TODAY:Christmas forecast warns of an onslaught of rain, snow for California
