Hurricane Gilbert, which devastated Jamaica in 1988, and Hurricane Hugo, which battered South Carolina last September, may have signaled a new era of monster storms, the director of the National Hurricane Center warned Friday. "If what we've seen in 1988 and 1989 are indications of the future, indeed stronger and more frequent hurricanes are coming," Robert Sheets told a conference on beach preservation at the St. Petersburg Hilton and Towers.
The past two Atlantic hurricane seasons produced five storms with winds of more than 130 mph, the greatest number of major hurricanes since the early 1960s. Gilbert - dubbed the "storm of the century" - had the lowest barometric pressure ever recorded for an Atlantic hurricane, while Hugo proved the costliest storm in U.S. history.
At some point in their development, both Gilbert and Hugo reached maximum Category 5 strength, generating storm tides of more than 18 feet and winds in excess of 155 mph.
Sheets said researchers have found a correlation between moisture levels in west central Africa - the birthplace of many hurricanes - and the frequency of tropical storms. After several years of drought, moisture levels are again on the rise and the result may be more and bigger hurricanes.
But despite the enormous threat, he said, emergency planners have poorly prepared for the worst case - when residents of coastal areas are unable to flee approaching storms because of a blocked bridge or flooded roads.
"I don't think it's morally or legally responsible to say, '5,000 of you are trapped, we're sorry, but you're on your own,' " Sheets said.
Sheets urged planners to give more thought to "vertical evacuation," the controversial idea of sheltering refugees in high-rise buildings. New Orleans, which lies below sea level and could be under 18 feet of water in a major hurricane, is developing plans to use downtown hotels as shelters.
Evacuating all of New Orleans would take 72 hours, "and there's no way we're going to give them 72 hours' notice," Sheets said. "They've got to deal with the issue of vertical evacuation."
In return for being allowed to build in vulnerable coastal areas, Sheets said, developers could be required to construct certain areas of their projects to be suitable as "refuges of last resort."
Ideally, a designated shelter would be above flood level and sit some distance from the water - in Hugo, even a 12th-floor apartment in one oceanfront building sustained such heavy damage that any occupants might have been killed.
The drawback of using vertical shelters, Sheets acknowledged, is that more residents might be tempted to ride out hurricanes on vulnerable barrier islands. "It's the kind of thing where you almost don't want them to know (the shelters) are there so you don't encourage them to stay," he said.
Sheets said hurricane forecasting might be helped by a plan to transfer the responsibility for hurricane reconnaissance flights from the Department of Defense to the Department of Commerce. Defense officials have long maintained that the flights are not part of their mission, and that weather forecasters should be able to get adequate information from satellites.
But Sheets said the 1989 hurricane season demonstrated the drawbacks of relying solely on satellites to predict a storm's strength and path. While Hugo was east of the Caribbean islands, satellite data indicated it was a moderate, Category 3 hurricane.
Subsequent reconnaissance flights found it was actually a Category 5 hurricane, capable of catastrophic damage.
A few weeks later, forecasters using satellite information miscalculated Hurricane Jerry's position by more than 100 miles. As a result, residents of Galveston, Texas, where Jerry eventually came ashore, had only eight hours' notice to evacuate.
"We weren't too proud of that forecast," Sheets said.
In general, residents of coastal areas have heeded hurricane warnings. Most South Carolina beach communities were evacuated with "three or four hours to spare" before Hugo struck, Sheets said. The hurricane center will continue its new policy of providing frequent live television updates on a storm's progress because, he said, "we find it has a very calming effect."