Meteorologists at the NOAA Climate Prediction Center released the latest seasonal outlook for the US, which reiterates previous predictions that this winter is likely to be warmer than the 30-year norm (1971-2000) over much of the nation, yet cooler than last year's very warm winter season.

NOAA's heating degree day forecast for December, January and February projects a two percent warmer winter than the 30-year average but about eight percent cooler than last year. Meanwhile, a strengthening El Niño event continues to develop in the equatorial Pacific. Although there has been early season snowfall in Buffalo and wintry weather in the upper Midwest and Rockies this month, NOAA's seasonal meteorologists say there is not much correlation between fall weather and the winter season.

The seasonal outlook
Overall, for December 2006 through February 2007, seasonal forecasters expect warmer-than-average temperatures across parts of the West, Southwest, Plains states, Midwest, parts of the Northeast and northern mid-Atlantic region, as well as most of Alaska. Near-average temperatures are favored for parts of the Southeast, while below-average temperatures are anticipated for Hawaii. Maine, the southern mid-Atlantic region, the Tennessee Valley, much of Texas and California, and the intermountain West have equal chances of warmer, cooler, and near-normal temperatures this winter. "Cooler-than-normal winter temperatures over Hawaii are still quite mild, with highs in the major cities expected to be in the 70s," said Michael Halpert, head of forecast operations at the NOAA

Climate Prediction Center
The precipitation outlook calls for wetter-than-average conditions across the Southwest from central and southern California to Texas and for Florida and the south Atlantic Coast. Drier-than-average conditions are favored in the Ohio Valley, the northern Rockies and Hawaii. Other regions have equal chances of drier, wetter or near average precipitation.

NOAA's Seasonal Drought Outlook, also updated, reflects the pattern of rainfall expected this winter. This pattern is expected to improve drought conditions across Arizona, Texas, portions of the Plains and Southeast. Drought is predicted to develop across parts of Idaho, Washington and Oregon.

The strength and impacts of El Niño
At present, weak El Niño conditions (warmer-than-average sea surface temperatures in the tropical Pacific, and other indicators) have developed across the tropical Pacific during the past few months. Current conditions and various forecasts imply that El Niño conditions may strengthen during the next few months. "However, this event is not expected to reach the magnitude of the very strong 1997-1998 El Niño episode," said Vernon Kousky, research meteorologist at the NOAA Climate Prediction Center.

El Niño events influence the position and strength of the jet stream over the Pacific Ocean, which in turn affects the winter precipitation and temperature patterns across the US. The NOAA Climate Prediction Center is responsible for forecasting and monitoring El Niño events for the US. Over the years, NOAA scientists have found that there tends to be some variety in impacts among El Niño events. The stronger the event, the more likely it becomes that much of the nation will experience a warmer than average winter.

Source: NOAA

•Date: 20th October 2006• Region: US •Type: Article •Topic: Warnings
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