Weather experts are predicting that some 17 Atlantic storms — about seven more than average — will pack enough strength they’ll reach tropical storm strength in 2008, earning the right to be named and carrying the potential to reach hurricane status.
The best guess for the number of hurricanes, according to weather forecasters at the Colorado State University Department of Atmospherical Science: Nine, which is above average (2.3); with five of those expected to be “intense hurricanes” reaching category 3, 4 or 5.The prognosticators raised the numbers of anticipated hurricanes and tropical storms over earlier predictions because early-season tropical storm activity and warmer than average Atlantic ocean waters point toward a busier hurricane season.
“The 2008 Atlantic basin hurricane season has gotten off to a very fast start. Four named storms have already formed this year, including Hurricane Bertha, which was the longest-lived tropical cyclone that has ever formed during the month of July. Hurricane Dolly made landfall as a Category 2 hurricane in south Texas on July 23.,’’ the researchers reported on Aug. 5, even as the fifth named storm of the season Edouard made landfall at Galveston, Texas.
Could global warming be a factor in the increase of hurricanes since 1995, particularly those strong hurricanes that make landfall like Katrina and Rita, among others?
The CSU researchers don’t believe so.
“Although global surface temperatures have increased over the last century and over the last 30 years, there is no reliable data available to indicate increased hurricane frequency or intensity in any of the globe’s other tropical cyclone basins besides the Atlantic,” they say in their August 1 report.
“In a global warming or global cooling world, the atmosphere’s upper air temperatures will warm or cool in unison with the sea surface temperatures.”
The driving force behind increased hurricane formation in the last decade is more likely the “increase in the Atlantic Ocean thermohaline circulation (THC)” and changes in ocean salinity, togehter known as “Atlantic Multidecadal Oscillation (AMO).”
The two scientists authoring the report compared the number of hurricanes making landfall during a weak cooling trend early in the 20th Century and the number making landfall during the later third of the century, when temps were warming. Their work found that more hurricanes made landfall in the U.S. during the first period, even though some of the most destructive hurricanes occurred during the latter period, including 2005’s Katrina.
“We should not read too much into the two hurricane seasons of 2004-2005. The activity of these two years was unusual but well within natural bounds of hurricane variation,” reported Philip J. Klotzbach and William M. Gray.
The CSU forecast models are newly developed, and based on several predictors that correlate to storm activity, such as previous storm seasons, Atlantic surface water temperatures, atmospheric temperatures and tropical storm activity.