AccuWeather.com 2006-07 Winter ForecastUpdated: Wednesday, October 18, 2006 2:01 PM
El Niņo To Have an Effect, But How Much?
AccuWeather.com Chief Long-Range Forecaster Joe *****i believes that the current El Niņo pattern will be one of the factors that determines the nature of the coming winter, but that the government's weather service is overplaying its effects. Unlike the National Weather Service forecast, *****i does not see this winter being warmer than normal across the vast majority of the country. Overall, the AccuWeather.com Winter 2006-2007 Forecast calls for a cooler-than-normal winter along the East Coast and eastern Gulf Coast, and a warmer-than-normal winter from the western Great Lakes to the Pacific Northwest.
An El Niņo - a cyclical occurrence of warmer-than-normal Pacific waters - can have repercussions on worldwide weather patterns, particularly a strong El Niņo, which features water temperatures that are significantly warmer over a broad expanse of tropical ocean. However, *****i's research points to an El Niņo that will remain at its current weak to moderate level, and may even weaken as the winter progresses. Because of this, a "typical" El Niņo winter - such as the one predicted by the National Weather Service last week - that features warmer-than-normal temperatures across much of the U.S. is not as likely to occur.
"We predict that the current El Niņo will not be only determinant of this year's winter weather," said *****i. "This year's winter will hinge on the timing and interaction of complex meteorological factors that would be overridden by a stronger El Niņo that others seem to be expecting."
One of these factors that *****i and his team expect to shape the upcoming season is the formation of a high pressure area over Greenland or northeastern Canada. This would force Arctic air down into the Northeast. If this occurs as expected, the Northeast could experience severe, prolonged cold - ten days or more of temperatures averaging five to ten degrees below normal - during the middle to late winter, most likely during the month of January.
"Signs are pointing to the possibility of a rough conclusion to winter for the Northeast," said AccuWeather.com Director of Forecast Operations Ken Reeves. "Examining past years where we see similar patterns to what we expect this winter bears this out. For example, the winter of 1992-1993 was moderate until early February, when it then became colder and snowier, and culminated with a harsh blizzard on March 13. Another of the winters we see a parallel to is 1957-1958, which again began more moderately, and concluded with significantly colder temperatures and major February and March snow storms."
*****i sums up his expectations for the upcoming December-to-February period this way: "The eastern U.S. will experience a colder-than-normal winter overall. The area from the eastern and central Great Lakes to the south-central and southwestern U.S. will experience near-normal winter temperatures. The region that stretches from the western Great Lakes to the Pacific Northwest will likely see above-normal temperatures."
*****i forecasts a wetter-than-average swath from southern and central California to the southern Plains and Southeast and up the East Coast, because an expected active subtropical jet stream will send storms on a track across the southern U.S. and likely ensure wet weather in the southern tier of the nation. How this moisture times itself with the arrival of colder air will determine how much snow the Northeast can expect, but winter is likely to be snowier than normal in the region - a mainstay of all winters since 2002. Very warm water relative to normal off all coasts provides ample moisture for any storm and, timed with cold air, would lend itself to heavy snowfall in the higher elevations of the Southwest and Southeast, and also the chance for some major coastal storms on the East Coast.
The pattern AccuWeather.com forecasts for the winter could lead to a significant problem next summer: the increased threat of wildfires. "The wetter pattern across the southern half of California and into the Southwest may spell yet another bad season for wildfires next year," said Reeves, "as the vegetation that flourishes this rainy season dies next year under the intense summer sun."
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