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.
Thank you for your patience during our recent Comments outage. Comments have returned, including comments on previous stories & blogs before the outage. As before, Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
Fog will continue to limit visibility and cause slick surfaces across Germany over the next several days.
A pair of storm systems will dampen Republic Day celebrations across India on Thursday.
Residents picking up the pieces after violent thunderstorms ripped through the southeastern United States will face the return of wintry air late this week.
Storms packing heavy rain and mountain snow will take a break beginning during the middle of this week, while further drought relief looks promising.
Hypothermia is one of the main concerns for anyone who spends extended time outside in the cold.
A multi-day outbreak of severe weather killed at least 19 people and brought devastation to communities across the Southeast on Saturday and Sunday.
Gusty winds and snow will sweep across the north-central United States through Tuesday night.
The death toll from rounds of severe weather across the South over the weekend has risen to at least 18.