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.
Tropical Depression Eight could become a tropical storm while brushing the North Carolina coast with rough surf, downpours and locally gusty thunderstorms into Tuesday night.
Following several stretches of unseasonable heat in August, September is set to yield lower temperatures across the United Kingdom.
Tropical Depression Nine developed just south of Florida on Sunday and will turn toward the northeastern Gulf Coast of the United States later this week.
Another strong tropical disturbance will move off the coast of Africa early this week and bears watching for strengthening and impact on the Caribbean and the United States during September.
Tropical Storm Lionrock is poised to make landfall in Japan on Tuesday afternoon local time with heavy rainfall, damaging winds and an inundating storm surge.
Following a stormy weekend across Germany, a period of dry and more seasonable weather is in store this week.
Three inches of snow fell in parts of the state; record lows were set in 31 northeastern U.S. cities and towns.
West Virginia (1989)
Lightning sets numerous house and trailer fires. Firefighters could not keep up with all the fires that were burning.
Incredible "snow" hurricane whitened parts of the Catskills.