In years with warm ocean water conditions, the Southeast Coastis the U.S. area most likely to be hit by hurricanes of highintensity, a meteorologist suggested in discussing some recentresearch.

Peter Dailey, director of atmospheric science at AIR WorldwideCorporation, said that every year since 1995, the Atlantic Oceanhas been warmer than average, and that trend will likely continuefor at least the next several years.

The firm has been researching hurricane activity spurred by warmwater conditions in an attempt to assess how long-term risk basedon all historical data differs from risk based solely on data fromhistorical years with warm ocean temperatures, he explained.

Mr. Dailey said the expectation under a warm ocean condition isan increased risk, over the long-term average, of tropical stormsand weaker hurricanes along the Gulf Coast and an increased risk ofhurricanes and stronger hurricanes along the Southeast U.S.Coast.

“If you look in the Gulf of Mexico, when the ocean is warm, themain impact…will be to increase the frequency of weaker hurricanesand tropical storms,” Mr. Dailey said.

“The impact along the Southeast Coast, which would extend fromthe southern tip of Florida to Cape Hatteras, N.C., is an increasein stronger hurricanes,” he added.

Speaking to how much change in activity the data showed, Mr.Dailey said “we're talking about on the order of 10-to-15 percentincreased frequency of weaker hurricanes along the Gulf Coast, andon the order of about 15-to-25 percent increased frequency ofhurricanes, including some stronger ones, along the SoutheastCoast. And that's an increase over the long-term average.”

Mr. Dailey said the reason why the Gulf Coast is at risk for anincrease in tropical storms and smaller hurricanes as opposed tolarger hurricanes with winds above 111 mph is because most stormsthat form in or near the Gulf of Mexico do not have a significantamount of warm ocean to travel over before they reach land.

“And that means they tend to not intensify to very strong stormsbefore making landfall,” Mr. Dailey explained.

Conversely, he said, “in the Southeast, the storms that makelandfall tend to originate over the center of the tropicalAtlantic, and this region is called the Main Development Region(MDR). And storms that form over the MDR have a large, expansiveocean to intensify over before they reach land.” As a result, Mr.Dailey said, these storms have a greater probability of reachinghurricane strength.

He noted that this research does not suggest a major storm couldnot and will not hit the Gulf Coast in a warm water year. Rather,he explained, it is meant to look at “how the long-term risk isaltered under the current climate conditions.”

For the coastline from Cape Hatteras to the tip of Maine, Mr.Dailey said, there is not enough available data to make anassessment as far as the types of storms for which that area may bemore at risk.

This is partly due to the historical lack of hurricanes makinglandfall in that area. “There have really only been a handful ofhurricanes that have made landfall along the Northeast Coast evenin the last hundred years,” Mr. Dailey said.

The research conducted by AIR Worldwide involved looking at thehistorical record for hurricane activity in the Atlantic basin, andthen focusing only on the years that experienced warm waterconditions.

These years accounted for roughly half of the years contained inthe historical record, which dates back to around 1900. “Becausewe're only working with half of the data when we measure the warmclimatology, the uncertainties associated with the results of thatanalysis will be higher than the uncertainties associated with along-term analysis based on all of the data because the sample sizeis smaller,” Mr. Dailey noted.

He also stressed that the probabilities reported in the researchare not intended to be a forecast for any given year. “You can'tassume that you're going to realize these probabilities in anygiven year,” he said.

Mr. Dailey said AIR is providing two catalogs of simulatedevents for its U.S. hurricane model.

The first catalog is the “standard catalog,” in which thesimulated events are based on all historical data. The secondcatalog is called the warm SST (sea surface temperature) conditioncatalog, which factors in the research regarding warm waterconditions.

“So what an insurance company would see under this warm oceancondition is this elevated risk of weaker hurricanes in the gulfand an elevated risk of all hurricanes, especially stronger ones,in the Southeast U.S.,” Mr. Dailey said.