HURRICANES: A PRIMER ON FORMATION, STRUCTURE, INTENSITY CHANGE AND FREQUENCY

Robert Hart, Florida State University
 HYPERLINK "http://www.marshall.org/pdf/materials/409.pdf" \t "linkWin" http://www.marshall.org/pdf/materials/409.pdf

The 2005 hurricane season devastated the lives of thousands of people on the Gulf Coast. Financial losses related to the hurricanes far exceeded previous records and the loss of life was the largest in the United States since the Florida Keys hurricane of 1928. This record-breaking activity has led to increased discussion of hurricane science. This primer examines the fundamentals of tropical cyclone formation, structure, movement, and frequency to better inform future discussions of hurricanes, their causes, and effects. [....]

6. Closing

It is worthwhile to note in closing that if we were to adequately prepare our homes and lives for the worst-case-scenario, based upon the past 100 years, we would be adequately prepared for any increase in intensity that may result from global warming.

The greatest threat to life and property results not from the increase in tropical cyclone intensity that may result from global warming, but instead from the inexperience, apathy, and disbelief we have about our own current and past vulnerability. A 5 or 10 mph increase in hurricane intensity (such as that which may result from climate change) should not make the difference for how the public prepares for a hurricane. Would the residents who were affected by Katrina, Rita, and Wilma in 2005 act any differently if the forecasts had been decreased or increased by 5 or 10 mph? Should the residents of New England have taken the devastating 1938 hurricane less seriously at the time because it preceded the global warming era?

Further, despite the dramatic activity of this past year, the percentage of land areas and population that have experienced hurricane or major hurricane (115mph or greater)force winds is astonishingly small. For example, during Hurricane Andrew, a Category 5 hurricane at landfall, Fort Lauderdale, which was only 65 miles from the center, experienced a maximum gust of only 61mph, well short of hurricane force. Although Andrew was a Category 5 hurricane, downtown Miami and the airport experienced Category 2-3 winds and Miami Beach experienced Category 1-2 winds. Hurricane Andrew was a truly devastating storm in areas close to the center (e.g., Homestead), but we must realize the vast majority of southern Florida experienced Category 2 or (considerably) less winds from Andrew. Although Andrew (1992; Category 5) was far more damaging in total than Hurricane Wilma (2005; Category 3), a far greater number of people experienced hurricane force winds during Wilma given its larger size.

This likely explains, in part, why much of southern Florida was surprised by the strength of the wind when it came. Many people thought they had already experienced a major hurricane wind with Andrew, but the vast majority had not, given Andrew's small size. In short, even though hurricanes severely affected many of the Gulf coastal population in 2004 and 2005, the percentage of people that experienced true hurricane force winds was minimal. That is to say, just because someone was affected by Hurricane Andrew or Rita or Katrina does not mean that she or he experienced the full strength of hurricane force winds, as those winds are confined close to the center of the storm.

After 50-100 years of additional hurricane record, we may at last know the magnitude, if it exists, of the impact of global warming on hurricane occurrence. Let us be hopeful that, regardless of this magnitude, the increased public attention produced by the recent scientific studies will lead to an increase in preparedness and a decrease in the loss of life. Whether or not global warming is increasing hurricane intensity and frequency should not be the immediate focus for public preparedness. Intense hurricanes have occurred frequently in the past, are occurring now, and will continue to occur in the future. As coastal property becomes more valuable and coastal population more dense, damages and loss of life will continue to grow.

FULL REPORT at  HYPERLINK "http://www.marshall.org/pdf/materials/409.pdf" \t "linkWin" http://www.marshall.org/pdf/materials/409.pdf