Busy Atlantic hurricane season expected

Sea conditions favor more storms than usual, forecasters say

May 23, 2007|By Frank D. Roylance | Frank D. Roylance,sun reporter

Just as Americans are beginning to think about the sunny seashore, federal hurricane forecasters were back yesterday, clouding the horizon with another ominous prediction for the coming Atlantic hurricane season.

Experts at the Climate Prediction Center said unusually warm sea-surface temperatures in the Atlantic and influences from the Pacific more favorable to storm development mean that Gulf and Atlantic coast residents should brace for above-average hurricane activity this season, which starts June 1.

Their forecast calls for 13 to 17 named storms this year, with seven to 10 gaining hurricane strength and three to five becoming Category 3 storms, with top sustained winds of 111 mph or higher.

That would be about double the number during last year's calmer-than-average season.

"Currently, it's not possible to predict the number or intensity of land-falling hurricanes or whether a given locality will be impacted," said Gerry Bell, the center's lead Atlantic forecaster.

Seasons with similar activity have historically had at least two storms make landfall in the United States, with two or three more going ashore in the Caribbean, he said.

Separately last month, Colorado State University scientists made predictions similar to the federal forecast.

CSU's Philip J. Klotzbach and veteran forecaster William M. Gray also said there is a 74 percent chance that the U.S. coastline will be struck by a Category 3 storm this season.

They forecast a 50 percent chance that a Category 3 storm will hit the U.S. East Coast. That is well above the 31 percent average for the past century.

If Americans are skeptical of springtime forecasts for a storm season than runs through Nov. 30, they can be forgiven. Similar predictions in the past two years were well off the mark.

In May 2005, forecasters for the National Oceanic and Atmospheric Administration predicted an active storm season with 12 to 15 named storms, including seven to nine hurricanes, three to five of them reaching Category 3.

That season turned out to be about twice as bad as was forecast, the most active and destructive Atlantic storm season on record.

There were 27 named storms, of which 15 became hurricanes. Of those, seven reached Category 3 power. They included an unprecedented four storms that reached Category 5, with top sustained winds of 155 mph or more.

Two of those, Katrina and Rita, caused catastrophic damage on the Gulf Coast and killed more than 1,500 people.

Forecasters were far off the mark again last year. After springtime predictions of a very active season, the Atlantic was fairly quiet, with nine named storms, of which five reached hurricane strength. Two reached Category 3, and none hit the U.S. coast.

Bell conceded that forecasters "overpredicted" last year's season. He blamed the quick development, late in the season, of El Nino conditions, unusually warm surface water temperatures in the tropical Pacific causing a shift in global weather patterns that tends to stifle hurricane development in the Atlantic.

But "last year's activity should not be considered as an indicator that the active era has ended," Bell said.

That "active era," climate scientists say, began in 1995, when multidecade cycles of oceanic and atmospheric conditions in the Atlantic combined for what is expected to be a 25- to 40-year stretch of unusually active hurricane seasons, interrupted at times by El Nino lulls.

Of the past 12 Atlantic hurricane seasons, nine have been more active than the long-term averages.

"Detailed published analysis shows that all the conditions associated with the active era are still in place," Bell said.

He noted two key climatic factors behind this year's forecast. The first is the continuation of water temperatures and atmospheric conditions in the Atlantic favorable to the development of storms. Those conditions have changed little since 1995.

The second is the dissipation of last year's El Nino. Forecasters are watching for possible unusually cool La Nina conditions in the Pacific this summer, which would encourage hurricane formation in the Atlantic.

Even if the Pacific remains "neutral," Bell cautioned, "conditions still favor an above-normal season" for Atlantic storms.

However the season plays out, federal officials said, there is deadly danger from tropical storm systems even in a "quiet" year. And that risk is growing.

"Our coasts are becoming more populated," said NOAA's administrator, Vice Admiral Conrad C. Lautenbacher, noting a 500 percent increase in the population of Florida from 1950 to 2000.

An estimated 153 million people - more than half of the nation's population - live within 50 miles of an ocean. Almost 40 million people from the Carolinas to Texas are counted among those most threatened by Atlantic hurricanes.

The value of coastal development in the path of future storms has grown along with the population.

Disaster planners at a conference in New York in July were told that if a strong Category 3 hurricane - like the one that came ashore on Long Island in 1938 - struck today, it would cause insured losses of $110 billion. That would be three times the devastation wreaked by Hurricane Katrina on the Gulf Coast in 2005. Total economic losses would be nearly twice that amount.

"Whatever the hurricane season may bring, we obviously hope for the best, but we prepare for the worst," said Homeland Security Secretary Michael Chertoff.

frank.roylance@baltsun.com

For more on hurricane preparedness, visit www.nhc.noaa.gov/HAW2/english/intro.shtml

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