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Federal Hurricane Experts Predict Slightly Above-Average Season

Tribune photo by CHRIS URSO

Lead Hurricane Seasonal Forecaster with NOAA Climate Prediction Center Gerry Bell speaks at MacDill Air Force Base.

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By NEIL JOHNSON | The Tampa Tribune

Published: May 22, 2008

Updated: 05/22/2008 11:22 am

TAMPA - Conditions are in place for another active hurricane season, and government scientists think 2008 will have an above-average number of storms.

Gerry Bell, lead seasonal forecaster with the National Climate Prediction Center, said today that there should be 12 to 16 named storms this season, and that six to nine of those will become hurricanes.

He also said two to five of those hurricanes will grow to Category 3 or stronger storms.

The National Oceanic and Atmospheric Administration team of scientists who put together the season's forecast do not give a specific number of storms they expect. They also do not predict which, if any, will strike land or the United States.

NOAA's prediction would mean a season with more hurricanes than the average, which is 11 named storms, six hurricanes and two major hurricanes.

The prediction follows a trend of more active seasons that started in 1995, Bell said. The Atlantic Ocean entered a phase of more active hurricane seasons 13 years ago that could last another 12 to 27 more years.

"There's no indication this period has ended," Bell said as NOAA unveiled its seasonal prediction at MacDill Air Force Base, where the agency's two hurricane hunter aircraft are based.

In addition to the period of heightened hurricane activity, Bell said lingering effects on the atmosphere of a La Niña also pointed to a more active season.

Though the La Niña, when water in the equatorial Pacific Ocean cools a few degrees below normal, may be gone by the summer, it could still play a role in this hurricane season.

The La Niña causes shifts in the jet stream that reduce winds that disrupt developing hurricanes. Seasons during a La Niña typically have more hurricanes that when the Pacific Ocean is at its normal temperature or warmer than normal.

This year NOAA officials stressed that any forecast may not be 100 percent accurate.

Bell said agency scientists are 60-70 percent certain the number of storms will be within the forecast range. But there's also a 25 percent chance of a near-normal season and 10 percent possibility the season will produce fewer than normal storms.

Last year, NOAA predicted 13-17 named storms, seven to 10 hurricanes and three to five major storms with winds topping 111 mph, or Category 3.

The total number of storms was within NOAA's predicted range, but the season produced only six hurricanes and just two reached major storm strength.

Those were hurricanes Dean and Felix, which became the first two Category 5 hurricanes to hit land in the same season since modern records started in 1850.

Most storms last season did not become strong and did not last long. One hurricane, Humberto, hit the United States in 2007 as a Category 1 storm that quickly shrank to a tropical storm after landfall in Texas.

Bell said 2007 was a busy hurricane season, but the prediction was flawed in other ways.

"What missed was the overall intensity and duration of the storms," he said.

NOAA didn't do enough to make the public understand any forecast has a possibility of being wrong, said Louis Uccellini, director of the National Centers for Environmental Prediction that includes the center were Bell works.

"We don't have the skill level to predict the exact number of storms," Uccellini said. "But climate conditions point to an active season."

Those conditions include rainfall in tropical west Africa and the Amazon basin, Bell said. Rain that is above average in Africa and below average in the Amazon create winds in the atmosphere favorable for hurricanes, and that has happened since the Atlantic entered the active phase in 1995.

Rainfall patterns in the two continents were exactly opposite from the 1970s through 1994, when the Atlantic was in a tranquil period for hurricanes.

NOAA's expectations of an above-average season mirror the April seasonal forecast by William Gray and Phil Klotzbach of Colorado State University. They forecast 15 named storms, with eight becoming hurricanes and four of those growing into major storms.

Unlike NOAA, Gray and Klotzbach forecast a specific number of storms.

They will issue a revised forecast June 2, the day after hurricane season starts. NOAA will revise its forecast in August when hurricane season begins its busiest 10 weeks. The season ends Nov. 30.

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