John Grymes | 7/2/2005 2:09:44 AM
Hurricane and tropical storm counts have been above the norm for all but one of the last 10 years. This trend and historical records suggest that the Atlantic is in an elevated storm count for another 10 to 20 years, according to LSU AgCenter climatologist Jay Grymes.
That’s not good news for Louisiana. Coastal communities and coastal industries, like the state's oil and gas sector, as well as south Louisiana farmers, need to evaluate the potential consequences of increased storminess.
"Preparedness and efforts to mitigate the impacts of these storms have never been as important as they are right now," Grymes says.
"Although record-setting losses (estimates of upwards of $40 billion or more) attributed to 2004's tropical weather may be unusual even during ‘active’ hurricane seasons, the United States should prepare for more frequent and more costly landfalls in the coming years," the climatologist advises.
Growth along the Atlantic and Gulf coasts has been unprecedented in the last 20 years, putting more people and more property within reach of the impact of tropical systems. The same is true to some extent for the Bayou State. There is more development in and along Louisiana's coastal zone than ever before.
"The coastal zone and its extensive marshes have long stood as a protective barrier against tropical weather, but given today's fragile condition and rapid loss of that environment, coupled with the threat of more frequent landfalls in the upcoming years, we could be facing the potential for social, economic and environmental losses of disastrous proportions," Grymes says.
What accounts for this increased tropical storm activity? Warmer-than-normal sea-surface temperatures provide added energy to support and strengthen tropical cyclones. For the atmosphere, slight reductions in air pressure near sea level coupled with a general weakening of winds above the surface and into the middle levels of the atmosphere also enhance the development of tropical storms.
"When all three ingredients are there, the Atlantic Basin is primed for increased tropical activity," Grymes says.
"And that is precisely what tropical weather scientists believe that they have been seeing over the past 10 years.
"Indeed, the onset of this enhanced phase appeared in dramatic fashion during the 1995 hurricane season, with that year's 19 named storms ranking as the second most active season of the long-term storm record," Grymes points out.
Historical records indicate a run of reduced storminess over the Atlantic Basin from the beginning of the 20th century into the late 1920s. Average-annual storm counts increased markedly from the 1930s through the 1960s, with a return to "quieter" activity during the 1970s, 1980s and early 1990s. These three periods closely coincide with shifts in average seasonal surface-water temperatures of the Atlantic Ocean.
These records suggest that the increased activity that we have observed since the mid-1990s may be the ‘new norm,’ at least for the next decade or two," Grymes forecasts.
For information on related topics, visit the AgCenter Web site at www.lsuagcenter.com/. For local information and educational programs, contact an extension agent in your parish LSU AgCenter office.