WBZ Weather Almanac

Increased Atlantic Action... A Multi-Decade Threat

Christopher Landsea, NOAA Hurricane Research Division, Miami, FL

The devastating hurricane season of 2004 is not an aberration in fact, it is likely to be the norm for the next 15 to 30 years. Major hurricanes tend to occur in cycles of active and quiet periods that can last for decades. These long, slow flip-flops are due to a natural fluctuation of water temperatures and atmospheric conditions governed by the Atlantic Ocean. In the active major hurricane periods, strong systems develop more frequently because warmer sea surface temperatures provide more energy to hurricanes. At the same time, the atmosphere features minimal wind shear keeping a storm's circulation intact. In contrast, the quiet eras correspond with slightly cooler waters and more windshear disrupting the growth and development of tropical systems.

It appears that around 1995, a 25-year slow phase marked by fewer major hurricanes ended and an active period began. This new phase has made for busy hurricane seasons with multiple threats like Charley, Frances and Ivan expected to be commonplace during the next few decades. Florida, in particular, is expected to see a doubling in major hurricane landfalls. The last time three hurricanes hit the state in one year was in 1964. The damage back then was serious, but today, the toll is far worse.

While Florida has seen the brunt of major hurricanes of recent, New England is also at increased risk of a hurricane, even a major system. In the five decades of active hurricanes in the middle of the 20th Century, New England was struck by five major hurricanes 1938, 1944, Carol (1954), Edna (1954) and Donna (1960). The only major hurricane to strike during the quiet period that followed was Gloria in 1985. Thus, it is likely that New England will again see a major hurricane over the next decade or two, if this active period does indeed continue.

A Multi-Decade Threat

Population in coastal communities in Florida and elsewhere has dramatically increased, climbing 41% between 1960 to 1990. The region with the highest coastal density (almost 60 million people in 285 counties) is the Atlantic Coast. Much of this coastal population makes up the "megalopolis?extending from southern Maine through northern Virginia, including Boston and Providence, accounting for nearly a quarter of the U.S. population. In fact, 90% of residents in Maine and Massachusetts live in coastal counties. In addition, U.S. residents are twice as wealthy per capita today with twice as many possessions than 40 years ago. These changes in population density and wealth contribute to the increased destruction and human impact we experience today when compared with past hurricanes, setting the stage for disaster.

Projections of major hurricane strikes and population/wealth changes over the next 20 to 30 years lead to some startling conclusions. We anticipate that in the United States, the rate of economic loss due to hurricane landfalls will be about six to eight times the cost recorded back in the 1970s, 1980s and 1990s. Families and businesses up and down the east coast and those in New England need to be aware of the impending frequency of major hurricanes, take the threat seriously and prepare accordingly.

As the sage old saying goes, we should hope for the best, but prepare for the worst.

Christopher Landsea is a Research Meteorologist for the National Oceanic and Atmospheric Administration's (NOAA) Hurricane Research Division in Miami, Florida. He has studied hurricanes for 15 years and has flown into and around 20 hurricanes aboard NOAA and NASA aircraft.