NOAA: El Niño to Help Steer U.S. Winter Weather

October 15, 2009

Winter Outlook - Precipitation

High Resolution (Credit: NOAA)

El Niño in the central and eastern equatorial Pacific Ocean is expected to be a dominant climate factor that will influence the December through February winter weather in the United States, according to the 2009 Winter Outlook released today by NOAA’s Climate Prediction Center. Such seasonal outlooks are part of NOAA’s suite of climate services.

“We expect El Niño to strengthen and persist through the winter months, providing clues as to what the weather will be like during the period,” says Mike Halpert, deputy director of the Climate Prediction Center – a division of the National Weather Service. “Warmer ocean water in the equatorial Pacific shifts the patterns of tropical rainfall that in turn change the strength and position of the jetstream and storms over the Pacific Ocean and the U.S.”

“Other climate factors are also likely to play a role in the winter weather at times across the country,” added Halpert. “Some of these factors, such as the North Atlantic Oscillation are difficult to predict more than one to two weeks in advance. The NAO adds uncertainty to the forecast in the Northeast and Mid-Atlantic portions of the country.”

Highlights of the U.S. Winter Outlook (December through February) include:

This seasonal outlook does not predict where and when snowstorms may hit or total seasonal snowfall accumulations. Snow forecasts are dependent upon winter storms, which are generally not predictable more than several days in advance.

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