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Storm predictors

Early forecasts of the 2009 hurricane season project below-average activity, with fewer named storms than the past five years. The precision of such forecasts, many experts say, is about as reliable as flipping a coin.

Still, a few factors help feed or hinder hurricane activity, and April is the month these atmospheric wonders are scrutinized. Come late May, accuracy improves, said Jeff Masters, founder of Weather Underground (wunderground.com). The National Hurricane Center in Miami won't even release predictions until then.

Here are four phenomena used to predict this year's Atlantic hurricane season:

La Nina vs. El Nino: We’re in a weak La Nina cycle, which can boost hurricane development. Any transition to El Nino would likely happen this month, said Masters. In an El Nino cycle, energy from warm Pacific waters funnels eastward and settles over the Atlantic, breaking up hurricanes. So El Nino can be good for Florida.

Sea Surface Temperature: Well-known Colorado State University researchers Bill Gray and Phil Klotzbach noted a cooling of Atlantic sea surface temperatures in predicting only six hurricanes this year, down from eight last year. That’s significant because we’ve been in a warm-water phase since 1995, and under normal conditions it’s about five to 10 years too early for a cooling shift.

African dust: One of the more fascinating conditions contributing to hurricane suppression is dust blowing off the coast of Africa. The thick cloud can cool the Atlantic enough to keep hurricanes from forming. The amount of dust depends on whether that region of Africa is in a drought. The last three or four years have been good for African crops, bad for Florida’s hurricane season.

Bermuda High: If a hurricane forms in the Atlantic, Floridians can hope for a well-placed Bermuda High. Depending on its location, the huge blob of high pressure, turning clockwise, can steer storms away from the eastern United States.

Storm predictors 04/12/09 [Last modified: Tuesday, April 14, 2009 3:50pm]

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