La Nina Could Mean More Santa Ana Winds this Fall
Sep 12, 2010; 3:14 PM ET
As the fall season gives way to a La Niña winter on the West Coast, the annual Santa Ana winds could be more frequent than usual.
Santa Ana winds are intense, dry offshore winds that affect Southern and Baja California in late fall and early winter. They originate from high pressure building in over the Great Basin and Mojave Desert regions, and cause air to funnel to the southwest through mountain passes.
Santa Ana winds can either be cool or warm, depending on the temperatures of their sources.
The upcoming winter will be in a La Niña pattern, which sets up a storm track over the Pacific Northwest that typically slights Southern California.
These bigger, more frequent storms in the Northwest are usually followed by frequent large areas of high pressure, which in turn fuel more Santa Ana winds that divert from the high pressure toward the Four Corners.
AccuWeather.com West Coast Expert Meteorologist Ken Clark said the current situation is setting up to be one of the strongest La Niña in the last decade.
Below-normal sea surface temperatures in the tropical Pacific are referred to as La Niña. The cooler the waters are, the greater the La Niña is.
"Given a La Niña winter and the Pacific temperature pattern, there could be more Santa Ana winds than usual," said AccuWeather.com Expert Senior Meteorologist Jim Andrews.
These dry winds are also notorious for fanning wildfires in the Southwest in the autumn months, and more winds would make wildfires harder to combat.
Much of the region has been suffering through drought conditions all summer. Much of Nevada and Arizona is classified as abnormally to moderately dry by the U.S. Drought Monitor.
"The fire risk will always be there," Andrews said. "La Niña winters typically mean less rainfall. This combined with dry offshore winds makes a multiplying effect on wildfire risk."
Clark said the worst of wildfire season is yet to come, adding that fire season could even be prolonged by La Niña.
"The longer La Niña goes, the first rain could be delayed. If that's the case, the fire season will last longer."
AccuWeather.com's Chief Meteorologist and Expert Long Range Forecaster Joe Bastardi is concerned the La Niña may persist well past this winter.
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By Gina Cherundolo, AccuWeather.com Staff Writer
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