Prediction factors

Published: Updated:
MGN Online

FORT MYERS, Fla. – There are a few factors that largely control the Atlantic hurricane activity. This year, those factors are expected to come together to produce fewer tropical storms and hurricanes this 2015 season.

First, a strong El Niño has formed. El Niño occurs when warmer-than-average temperatures are experienced in the eastern and tropical Pacific.  Hurricane formation requires the wind to be fairly uniform throughout the atmosphere, meaning they require low vertical wind shear. An El Niño creates higher vertical wind shear in the Atlantic basin which suppresses hurricane formation.

Second, we are experiencing cooler-than-average water temperatures in the central and eastern Atlantic.

The third reason for the below average prediction, we are seeing higher-than-average sea level pressures are being recorded in the Atlantic basin.

During an El Niño, we tend to see a strengthening of the Atlantic subtropical ridge. If the pressure in this area is higher than normal, trade winds in the Atlantic basin become stronger. This enhances ocean mixing and upwelling causing cooler sea surface temperatures. The heat of the water provides the energy these tropical storms need to build. Hurricanes rely on warm seawater to release heat into the upper atmosphere, so below normal tropical activity usually occurs when water temperatures are below normal.

From 1970 to 2008, the number of storms during an El Niño summer decreased drastically from that of a neutral or La Niña summer.

Putting statistics aside, strong storms have formed and impacted Florida and the United States during El Niño years and remember, it only takes one storm to make an active season here in Southwest Florida.

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