Storms are lined up for thousands of miles over the northern Pacific.
According to AccuWeather Senior Meteorologist Brett Anderson, "The pattern over the Pacific Ocean is beginning to take on the look of El Niño."
El Niño occurs when tropical Pacific waters are warmer than normal, and the pattern can last several months to a couple of years. During the winter, a strong El Niño can produce frequent storms along part or much of the west coast of the United States.
See recent winter weather across the US:
Snow, winter weather 2015-2016 season across the U.S.
Persistent northwest US storms to unleash feet of rain, snow into next week
LUBBOCK, TEXAS - DECEMBER 27: A highway worker tries to shield himself while walking to his truck on December 27, 2015 in Lubbock, Texas. Coming on the heels of several strong tornadoes, some northern parts of Texas are experiencing blizzard conditions with wind gusts up to 50 mph and as much as 13 inches of snow forecast. (Photo by John Weast/Getty Images)
NEDERLAND, CO - DECEMBER 15: Steve Hauser plows snow in the Caribou Shopping Center in Nederland, Colorado on December 15, 2015. Snow is expected to continue throughout the day. (Photo by Helen H. Richardson/The Denver Post via Getty Images)
NEDERLAND, CO - DECEMBER 15: A yellow lab waits patiently in his owner's snowy old truck along East 1st Street in Nederland, Colorado on December 15, 2015. Snow is expected to continue throughout the day. The dog looked warm and didn't wait long in the car as his owner returned shortly after an errand in the town. (Photo by Helen H. Richardson/The Denver Post via Getty Images)
DENVER, CO - DEC. 15: Anna Renton, 7, right, relaxes while neighbor Graham Langner, 7, has a snow fight with his nanny, Ashely Kish.The Denver metro area received more snow than expected overnight, closing schools across the city with some areas measuring a foot of snow by the early morning. (Photo by Kathryn Scott Osler/The Denver Post via Getty Images)
LAKEWOOD, CO - DECEMBER 15: Crut Liles clears snow from his walkways outside his home in Lakewood, December, 15, 2015. Many schools in the area are closed due to the snow storm. (Photo by RJ Sangosti/The Denver Post via Getty Images)
DENVER, CO - DEC. 15: A CDOT crew runs their plow truck southbound on Colorado Blvd. near E. 13th Ave. in Denver. The Denver metro area received more snow than expected overnight, closing schools across the city with some areas measuring a foot of snow by the early morning. (Photo by Kathryn Scott Osler/The Denver Post via Getty Images)
Al Frelk walks his dog, Shiba, 10, in Lords Park in Elgin, Ill., on Saturday, Nov. 21, 2015. Asked about the snow, Frelk said, 'It's beautiful, but can be tough to drive in. Though Shiba has been waiting 9 months for this.' The first winter storm of the season dropped more than 10 inches of snow at numerous Chicagoland locations. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
DENVER, CO - NOVEMBER 17: Snow hit the Denver metro area having an impact on air travel at Denver International Airport. They were clearing out from the snow on Tuesday, November 17, 2015. Raul Hernandez shovels snow in the economy lot. Hernandez and his crew had worked all night to clear snow. (Photo by Cyrus McCrimmon/The Denver Post via Getty Images)
LAKEWOOD, CO - NOVEMBER 11: Brandon Nelli, a student at Colorado Christian University in Lakewood, shovels snow during a Veteran's Day snow storm the moved into the area overnight, November, 11, 2015. Lakewood got almost 3 inches in some areas form the storm. (Photo by RJ Sangosti/The Denver Post via Getty Images)
DENVER, CO - NOVEMBER 11: A blanket of white snow covers Fort Logan National Cemetery during a Veteran's Day snow storm the moved into the area overnight, November, 11, 2015. (Photo by RJ Sangosti/The Denver Post via Getty Images)
MONUMENT, CO. - November 17: Bob Swift clearing his driveway of a deep drift of snow in Monument, CO. November 17, 2015 Monument, CO (Photo By Joe Amon/The Denver Post via Getty Images)
An above-average amount of snow covers a small cabin near where the first snow survey of winter conducted by the California Department of Water Resources in Phillips, California December 30, 2015. REUTERS/Fred Greaves
Cameron Shonnard backflips a jump at Squaw Valley in Olympic Valley, California, December 5, 2015. An El Nino is forecasted for California, and regular precipitation has been welcomed after years of drought. REUTERS/Max Whittaker TPX IMAGES OF THE DAY
Fresh snow clings to trees near Big Bend, California, December 4, 2015. An El Nino is forecasted for California, and regular precipitation has been welcomed after years of drought. Picture taken December 4. REUTERS/Max Whittaker
The U.S. Capitol dome can be seen behind piles of snow removed from parking areas and walkways around the Capitol grounds in Washington January 26, 2016. The snowbound Washington area was resuming partial business on Tuesday as trains and buses restarted near-normal service, while federal offices remained closed following a massive blizzard that hammered the U.S. East Coast. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY
Floodwaters cover Green Avenue after a winter storm in Manasquan, New Jersey, January 24, 2016. A morning high tide surge of 2 feet followed snowfall of about 2 feet in the first major storm of the season. REUTERS/Dominick Reuter
A couple poses for a photo on a snow pile during a snow storm in Times Square in the Manhattan borough of New York, January 23, 2016. REUTERS/Carlo Allegri TPX IMAGES OF THE DAY
WASHINGTON, DISTRICT OF COLUMBIA, UNITED STATES - 2016/02/15: Snow is once again falling across Washington, D.C on Monday, 15 February 2016. The bitter cold was replaced by snow, sleet and rain Monday in the mid-Atlantic states and the South, but many residents were able to hunker down at home with federal offices and many businesses closed for Washington's Birthday. (Photo by Probal Rashid/LightRocket via Getty Images)
A barn painted with the U.S. flag is seen in the snow covered field in Kanawha, Iowa, United States, January 16, 2016. Iowa will be the first state to hold its primary, with both Democratic and Republican events being held February 1, 2016. Picture taken January 16, 2016. REUTERS/Jim Young
Police officers gather outside the Montgomery County Courthouse, where actor and comedian Bill Cosby will arrive for a preliminary hearing on sexual assault charges, in Norristown, Pennsylvania February 2, 2016. Cosby has been charged with the 2004 sexual assault of Andrea Constand, a former women's basketball team manager at Temple University in Philadelphia, Cosby's alma mater. REUTERS/Mark Makela REUTERS/Mark Makela
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The El Niño storm train will deliver a heavy cargo of rain, high country snow and gusty winds to coastal areas from northern California to British Columbia.
Through the middle of the month, a few yards (meters) of snow will fall on the higher western slopes Cascades with 1-2 feet (300-600 mm) of rain in coastal areas.
The same pattern will deliver significant moisture to areas east of the Cascades in Washington and Oregon.
The storms will vary in strength and exact path and will generally arrive on the coast every one to three days.
Nearly every storm through next week will bring the risk of flash and urban flooding, coastal flooding, mudslides and sporadic power outages.
Through early next week, snow levels will be high enough that most storms will bring only rain to low-lying coastal areas and across central and eastern Washington and Oregon.
However, snow levels will be low enough during all or part of the storms to bring periods of accumulating snow and slippery travel to the passes in the Cascades of Washington and Oregon into early next week.
During the second half of next week, colder air will begin to press southward and inland over the West as moisture continue to stream in from the Pacific Ocean.
The pattern will allow snow to spread southward over the Sierra Nevada and eastward into the various ranges of the Intermountain West and eventually the Rockies. Some rain showers may reach parts of Southern California with the setup starting later next week.
According to AccuWeather Long Range Meteorologist Ben Noll, "The evolution of the El Niño pattern should direct storms farther south [on the Pacific coast] later in December, but more so during January and February."
How wet the pattern gets in Southern California is still uncertain.
According to AccuWeather Senior Meteorologist Kristina Pydynowski, "While some snow may fall over lower elevations of the Intermountain West, the air will still not be cold enough for snow along the Washington and Oregon coasts later next week."
There is a chance the weather may get cold enough to allow a rain and wet snow mix later next weekend to places like Seattle.
Meanwhile, as colder air again dips into the West, temperatures could spring toward record high levels in the Eastern states later next week and next weekend.