Hurricane season has been a dud despite dire forecasts

Doyle Rice | USA TODAY

The preseason predictions were all dire, using words like "extremely active" and "above-normal" to describe the forecast for the 2013 Atlantic hurricane season. The National Oceanic and Atmospheric Administration (NOAA) predicted that seven to 11 hurricanes would form, while AccuWeather predicted eight.

However, the season so far has been a welcome if unexpected dud, with not a single hurricane yet through the first week of September. (A typical full June-November hurricane season, based on weather records that go back to 1950, has seven hurricanes.)

In fact, the season is about to enter record territory for its unusual lack of hurricanes:

"If the first hurricane of 2013 forms after 8 a.m. on Sept. 11, it would set a record for the latest 'first' hurricane to arrive in the satellite era (1967 and later)," says Dennis Feltgen, spokesman with the National Hurricane Center in Miami. He says the current record holder is 2002's Gustav, which formed on Sept. 11 of that year.

The "satellite era" has increased the accuracy of hurricane counts: Once orbiting satellites were able to "spot" hurricanes that otherwise might have been missed, a more accurate count of the actual number of tropical storms and hurricanes each year became possible.

U.S. hurricane records go back to 1851, NOAA reports, but "because tropical storms and hurricanes spend much of their lifetime over the open ocean — some never hitting land — many systems were 'missed' during the late 19th and early 20th centuries," notes Chris Landsea, science and operations officer with the hurricane center.

Throughout history, there have only two years that had no reported hurricanes, according to AccuWeather: 1907 and 1914. However, considering there were only five reported tropical storms in 1907 and only one in 1914, that information is suspect.

As for all the other years that actually had hurricanes, the record latest "first" hurricane formed on Oct. 8, 1905, says Feltgen.

So, what's happened to all of the expected hurricanes this year?

Several tropical storms — of which there have been seven so far — dissipated when they ran into dry air and wind shear, Feltgen says, and did not affect the U.S. Wind shear — strong winds that roar from different directions at various levels of the atmosphere — can tear developing hurricanes apart.

Strong winds blowing west off of the Sahara Desert have helped bring dry, dusty air into the Atlantic this summer, which can tend to decrease hurricane formation, AccuWeather reports.

A tropical storm becomes a hurricane when its sustained winds reach 74 mph or greater.

"Several tropical waves coming across the tropical Atlantic in recent weeks have run into the same environmental issues and have failed to develop any further," Feltgen adds. Tropical waves are small weather disturbances that spin off the western Africa coast, which sometimes can strengthen into tropical storms and eventually hurricanes.

"Even though dry air has backed off a little in recent days, strong westerly winds aloft continue to interrupt tropical development for almost every budding system," according to AccuWeather hurricane expert Dan Kottlowski.

But now is not the time to get complacent, experts say:

"We are only at the midpoint of the six-month hurricane season, and have just entered the peak of the hurricane season (mid-August through late October)," Feltgen warns. "It is a mistake to believe that the second half of the season would resemble the first half."

"Hurricane formation in the Atlantic is overdue and is soon likely to shift in favor of multiple tropical systems," says Kottlowski.

As of late Friday afternoon, the hurricane center was monitoring three separate tropical disturbances in the Atlantic. However, none is forecast to develop into a hurricane.