A wave of frigid winter air forecast to sweep out of northwestern Canada and Alaska next week could bring single-digit and below-zero high temperatures to much of the United States through the third week of January, AccuWeather.com said Thursday.

The East, South, Midwest, Plains and Pacific Northwest areas will all feel the effects of the cold air mass, which will bring low temperatures that "will prove to be dangerous, if not life-threatening, where wind becomes involved," the forecasters said.

"The result of the cold may be several below-zero days for highs on the northern Plains and in the Upper Midwest, with potential for near-zero highs in parts of the Ohio Valley. Single-digit highs may be felt in the central Appalachians, with highs in the teens in parts of the South, and eventually the I-95 Northeast, as week three progresses, where the cold will take a round-about way in from the West."

Following record-cold December temperatures, AccuWeather.com chief long range forecaster Joe Bastardi earlier this week said this could be the coldest January for the nation since 1985 (see Daily GPI, Jan. 5).

Forecasters at Andover, MA-based WSI Corp., on the other hand, had expected warmer-than-normal temperatures across the eastern United States during January and February, with colder-than-normal temperatures taking over by late winter (see Daily GPI, Dec. 21, 2010). The emergence of a "more textbook La Nina pattern" was expected to help moderate those late winter temperatures, WSI said.

And forecasters at the National Oceanic and Atmospheric Administration said they expected the La Nina event in the equatorial Pacific Ocean to bring above-normal temperatures to a huge area stretching from the Rocky Mountains to the Mid-Atlantic through February, but said it was less clear how it would affect winter temperatures in the Northeast (see Daily GPI, Nov. 19, 2010).

"No doubt this year's La Nina is not living up to typical expectations," AccuWeather.com said. "However, you must remember that, similar to a bell curve in a college course grading system, not everything fits neatly in the middle. Additionally, there are other forces at work in the atmosphere and elsewhere that the meteorological community is just beginning to understand."

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