Active 2011 Atlantic hurricane season predicted by CSU forecasters

Forecasters at Colorado State University are predicting that the summer of 2011 will bring another active hurricane season to the Atlantic Basin.

Meteorologists Phil Klotzbach and William Gray think 16 named tropical storms will form between June 1 and November 30. Of those storms, nine will develop into hurricanes with winds of at least 74 mph, and five of those will intensify into major hurricanes with winds exceeding 110 mph.

Klotzbach and Gray think the active season will be fueled by very warm waters in the Atlantic Basin, which includes the Gulf of Mexico and the Caribbean Sea. The CSU forecasters also think that a weather phenomenon known as La Nina also will enhance storm formation in the Atlantic.

A La Nina event occurs when waters in the equatorial region of the Pacific Ocean are cooler than usual. The cooler waters often cause atmospheric conditions over the Atlantic Basin that allow tropical storms to develop. These favorable conditions can include diminished wind-shear. When wind-shear is high over the Atlantic, tropical storms have trouble forming and strengthening because the wind-shear disrupts their development.

If the 2011 hurricane season is active, it will continue a trend of busy seasons that began in 1995. Gray, a pioneer in the science of long-range hurricane forecasting, thinks this cycle of active seasons is caused by changes in salt content of the Atlantic waters. Salt level fluctuates because of ocean currents. An increase in the salt content makes ocean waters warmer, and hurricanes draw their enormous energy from warm water.

The cycle of active hurricane seasons can last 20 years or longer.

Last summer's hurricane season was the third-most active on record, but the activity went virtually unnoticed because no storm made landfall in the U.S. Meteorologists including Gray and Klotzbach don't think this kind of luck can continue.

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