Peak of hurricane season off to slow start

(Florida Today) -- Typically, September is the peak month for hurricanes.

But for the latest hurricane predictions, almost everything is dust and the wind.

"That seems to be the main factor keeping the activity down," John Pendergrast, a meteorologist with the National Weather Service in Melbourne, said of the recent conditions that have been dampening storms.

Over the past century, hurricanes and tropical storms have peaked around mid-September.

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But on Aug. 27, a forecast team at Colorado State University released a two-week forecast of hurricane activity through Sept. 10, predicting below average activity.

The team tries to predict what they call the Accumulated Cyclone Energy (ACE) index. That's all the named storms' maximum wind speeds for each six-hour period of the storms that happen over the two-week prediction period.

They say the two weeks ending Sept. 10 will bring less than 70 percent of the average ACE.

"The August 28-September 10 period is typically considered to be part of the most active part of the Atlantic hurricane season," wrote Phil Klotzbach, author of the CSU team's forecasts.

On July 31, the CSU team predicted 10 named storms for the hurricane season, which runs June 1 to Nov. 30. They expected four of those storms to strengthen to hurricanes and one of those hurricanes to be Category 3 or higher, with sustained winds of 111 mph or greater.

The lower-than-average prediction was primarily because of a cooling tropical Atlantic and a weak El Niño.

El Niño is a pattern of warmer than usual water in the Pacific Ocean that usually creates winds that shear apart storms before they can strengthen to hurricanes.

But when El Niño's not around, it's easier for hurricanes to build.

El Niño-like conditions may already be helping create stronger storm-dampening winds in the tropics, but Saharan dust that gets swept up into the atmosphere is also helping.

"It reduces the instability," Pendergrast said. "Because of that dust layer, the blocking characteristics of it is enough."

The CSU team's annual predictions are intended as a best estimate of tropical cyclone activity, not an exact measure.

A National Oceanic and Atmospheric Administration hurricane season prediction in early August also called for a below-normal season.

Predictions aside, preparations should remain the same, forecasters warn.

"Peopled definitely don't want to be complacent," Pendergrast said.

"There's still plenty of time for things to potentially develop."

This is CSU's 30th year issuing an Atlantic basin seasonal hurricane forecast (issued July 31):

• Named Storms: 10

• Hurricanes: 4

• Major hurricanes: 1

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