Ocean temperatures mean fewer hurricanes forecast for 2009

The 2005 tropical storm and hurricane season was the most active in recorded history. Named storms in the Atlantic and Caribbean waters started to be logged in 1851. In 2005, there were a record 28 named storms.

As far as the number of hurricanes, 2005 also broke the record with 14 storms, seven of these storms were considered to be major. The previous record was 12 hurricanes in 1969. The 2005 hurricane season will also go into the record books as the costliest ever.

The overall average is 10 named storms with six becoming hurricanes during a season, which began June 1 and will end Nov. 30.

Believe it or not, only three Category 5 storms have ever hit the U.S. mainland over the last 100 years. These were Camille in 1969, Andrew in 1992 and the Labor Day storm (no name) of 1935. In 2005, Katrina, Rita and Wilma did reach Category 5 status, but weakened before they made landfall.

The effect of warmer sea-surface temperatures definitely plays a role on hurricane development. According to a Time magazine article, between the 1920s and 1970, ocean waters were warmer and hurricane activity was high. However, as sea-surface temperatures cooled in the 1970s, 1980s and early 1990s, we saw a decrease in tropical storms and hurricanes.

Since 1995, ocean waters have generally turned warmer than normal again, leading to above average hurricane seasons, except during the big El Niño years of 1997, 2002 and 2006.

I believe that the 2009 tropical storm and hurricane season will have fewer named storms than normal, due to the rebirth of El Niño and the cooler than normal ocean temperatures off the African coast where tropical storms typically form. During an El Niño period, upper-level jet stream patterns are altered that decrease tropical storm formation in the Atlantic and Caribbean oceans as the tops of storms are sheared off.

I also expect to see approximately eight to 10 named storms with three to five becoming hurricanes.

A recent National Oceanic and Atmospheric Administration scientific paper indicated that fewer tropical storms and hurricanes are likely during much of the rest of this 21st century, especially if we see more global cooling down the climatological highway.

These respected scientists are forecasting 27 percent fewer named tropical storms overall, with 18 percent fewer storms that actually become hurricanes. Also, there will likely be at least 8 percent fewer major hurricanes like Katrina and Andrew above a Category 3. The National Oceanic and Atmospheric Administration claims that “increased wind shear in the tropics will actually cut the number of hurricanes.”