December blizzards in the Plains, Mid-Atlantic and New England and the wave of icy air that roared out of Canada and across the United States as far south as the Gulf Coast last week are the precursors to what could be the worst winter in 25 years, according to AccuWeather.com Chief Long Range Forecaster Joe Bastardi.

“It’ll be like the great winters of the ’60s and ’70s,” Bastardi said.

Typically, when below-normal cold periods arrive in winter they are limited to one region, but this winter the colder air is stretching over larger portions of the country, Bastardi said.

The winter of 2009-10 is shaping up to be similar to that of 1977-78, when nearly all of the United States east of the Rockies had a cold October followed by a warm November, with the cold returning in December, Bastardi said. January, February and March 1978 were all very cold relative to normal, according to Bastardi.

AccuWeather.com has said a weather pattern around Greenland would help a cold snap to settle over much of the eastern United States and portions of Europe for several weeks (see NGI, Jan. 4). During the coldest periods, an area stretching from New England to Atlanta could see daytime highs in the 20s. According to AccuWeather.com, heating oil prices could increase based on the demand caused by the cold temperatures. Weather-related shortages were reported in the Mid-Atlantic region after two feet of snow fell in the Washington, DC, area Dec. 19.

AccuWeather.com’s forecast was somewhat at odds with a recent outlook from Andover, MA-based WSI Corp., which called for warmer-than-normal temperatures in January in the Northwest and the Northeast except Pennsylvania, New Jersey and Delaware. According to the WSI forecast, almost all of the country can expect temperatures to average cooler than normal from January to March. WSI is forecasting 2,475 gas-weighted heating degree days during the three-month period, approximately 2.5% more than January-March 2009 and about 2% more than the 1971-2000 average.

The National Oceanic and Atmospheric Administration and Bastardi (see NGI, Oct. 19, 2009) have each said colder weather will dominate portions of the East through February, and each said the nation’s winter weather will be significantly affected by El Nino. But NOAA said it expected the current El Nino — the warming of surface temperatures in the central and eastern equatorial Pacific Ocean — to strengthen and persist through the winter, while Bastardi said El Nino will fade over the same period.

In a contrary forecast, WxRisk.com has said it expects the Midwest — not the East — to experience the coldest temperatures relative to normal this winter (see NGI, Nov. 2, 2009).

The current El Nino strengthened in December and is expected to continue at least into spring, according to a report last week from the National Weather Center’s Climate Prediction Center (CPC). Potential impacts include below-average temperatures across the South Central and southeastern United States and above-average temperatures and below-average snowfall across the nation’s northern tier (except New England), CPC said.

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