2nd polar vortex said unlikely

Federal forecasters predict average winter, few extremes

WASHINGTON — Last year’s harsh winter included cold blasts from a polar vortex and a lack of California rain, but no sequel is expected this year, federal forecasters said.

Mike Halpert of the National Oceanic and Atmospheric Administration said Thursday that the coming winter is expected to be pretty average. He doesn’t expect a lot of extreme conditions like last year’s cold snaps when Arctic air dipped south with the polar vortex.

“A repeat of last winter is not particularly likely,” said Halpert, acting director of the agency’s Climate Prediction Center in College Park, Md..

That doesn’t mean there won’t be cold air and snow, which is normal for much of the country during winter, Halpert said. It just won’t persist as much as it did last year, when extreme weather seemed to be stuck in place, he said.

Similarly, the high pressure ridge off the Pacific Coast that last year kept rain out of California during its crucial winter rainy season is unlikely to return in force, Halpert said.

The weather agency didn’t predict last winter’s extremes in last year’s winter forecast.

For December through February, the agency forecasts warmer-than-normal winter weather for most of the West, North and northern New England, with cooler weather in the Southeast, and average temperatures elsewhere.

The agency predicts wetter-than-normal conditions stretching from Southern California to Florida and up to northern New Hampshire, with dry patches in the Pacific Northwest and Great Lakes. Average precipitation is forecast elsewhere.

A long-expected El Nino — a warming of the tropical Pacific that changes weather worldwide — makes last year’s extremes less likely and the wetter, cooler south more likely, Halpert said.

Private weather forecasters are predicting a slightly cooler winter than the federal agency.

Judah Cohen, director of seasonal forecast at Atmospheric and Environmental Research in Lexington, Mass., has pioneered winter forecasts that link colder Eastern U.S. weather to years when there is more snow on the ground in Siberia in October. It’s still early and October isn’t finished, but the month has started out unusually snowy in Siberia, which preliminarily points to a cooler winter for east of the Mississippi River, he said.

Halpert said Cohen’s method is intriguing, but his agency would need to study more years to show the method works as a forecast tool.

Ryan Maue of the private Weather Bell Analytics of New York predicts that “a vast majority of the nation will experience significant periods of below-normal temperatures this winter, with the coldest temperatures [relative to normal] occurring in the Ohio Valley and up through the Eastern Plains.”