Winter 2011-2012: Big Swings for California, Northwest

October 11, 2011; 7:26 AM
Share |

NOTE: This forecast was published in October 2011; see our full-length 2012-2013 AccuWeather.com Winter Forecast for the latest information.


Apart from the Southwest, people across the western United States can expect large swings in weather conditions throughout the winter, according to the AccuWeather.com Long-Range Forecasting Team.

December is likely to feature above-normal warmth across much of the entire West. However, from late December into January, the team expects a transition where cold fronts will drop farther south along the West Coast, reaching northern and central California. This transition should bring temperatures back near normal, away from the interior Southwest.

The famed "Pineapple Express," a phenomenon that occurs when a strong, persistent flow of tropical moisture sets up from the Hawaiian Islands to the West Coast of the U.S., could develop for a time this winter. This phenomenon often leads to excessive rain and incredible snow events.

"Last year, California was hit hard when the Pineapple Express set up from Dec. 17-22, producing massive flooding and 13 feet of snow in the Sierra," Pastelok explained. "The Pineapple Express could develop for a period this winter and take aim at northern and central California. That could lead to monster snowfall and heavy valley rain with the risk of flooding and mudslides."

Snowfall is forecast to average out near or slightly above normal in the northern and central Sierra this year, depending on where the Pineapple Express sets up.

Above-normal rain and snowfall are also possible in the northern Rockies in January and in areas farther south and west during February.

Seattle and Portland are forecast to have a fairly typical winter with precipitation averaging out near normal. However, it will be a wet start to the season and frigid end. Near- to slightly above-average snowfall is expected in the Cascades.

Cold air focused over the northern Plains, Midwest and Great Lakes throughout the winter will likely spread farther west into the northern Rockies in January and February, though the worst of the cold for this region will last from February into March.

Winter Forecast for Southern California

Full AccuWeather.com Winter 2011-2012 Forecast

Comments

Comments left here should adhere to the AccuWeather.com Community Guidelines. Profanity, personal attacks, and spam will not be tolerated.

More Weather News

  • Los Angeles: Temperatures to Rebound Into Next Week

    April 24, 2014; 8:48 PM ET

    After a bout with lower temperatures early this weekend, temperatures will rebound for warm weather into early next week; however, a lack of rain will do little to alleviate the drought.

Daily U.S. Extremes

past 24 hours

  Extreme Location
High N/A
Low N/A
Precip N/A

WeatherWhys®

This Day In Weather History

Baltimore, MD (1991)
Hail 1-1/2" in diameter fell north of Baltimore City.

Mauna Kea & Mauna Lea, HI (1995)
6" of snow above 13,500 feet.

Mississippi & Alabama (1908)
Tornado swarm: 155 killed in Mississippi; 37 perish in Alabama.