2011 Atlantic Hurricane Season Forecast

The forecast for the Atlantic basin hurricane season of 2011 has been released by the Colorado State University Department of Atmospheric Science from Dr. Philip J. Klotzbach and Dr. William Gray.

They continue to foresee above-average activity for 2011, and above-average probability of a major hurricane landfall.

“We have decreased our seasonal forecast slightly from early December, due to anomalous warming in the eastern and central tropical Pacific and cooling in the tropical Atlantic.

This forecast is based on a new extended-range early June statistical prediction scheme that utilizes 29 years of past data. Analog predictors are also utilized. We expect current La Niña conditions to transition to near-neutral conditions during the heart of the hurricane season. Overall, conditions remain conducive for a very active hurricane season.”

Atlantic Hurricane Season June 2011 forecast 1950 – 2000 average
Named storms (>35mph) 16 9.6
Hurricanes (>72mph) 9 5.9
Major hurricanes (>111mph) 5 2.3
US landfall likelihood 72% 52%
Gulf Coast landfall 47% 31%

An interesting section of this year’s report is an analysis of wide-spread speculation that global warming is increasing hurricane activity. Using data back to 1945, there have been periods of increased activity during cooling trends, and decreased activity during warming.

“The U.S. landfall of major hurricanes Dennis, Katrina, Rita and Wilma in 2005 and the four Southeast landfalling hurricanes of 2004 – Charley, Frances, Ivan and Jeanne, raised questions about the possible role that global warming played in those two unusually destructive seasons. In addition, three category 2 hurricanes (Dolly, Gustav and Ike) pummeled the Gulf Coast in 2008 causing considerable devastation.

Some researchers have tried to link the rising CO2 levels with SST (sea surface temperature) increases during the late 20th century and say that this has brought on higher levels of hurricane intensity.

Hurricanes during cooling or warming

Hurricanes during global cooling or warming

These speculations that hurricane intensity has increased due to CO2 increases have been given much media attention; however, we believe that they are not valid, given current observational data.”

“For instance, in the quarter-century period from 1945-1969 when the globe was undergoing a weak cooling trend, the Atlantic basin experienced 80 major (Cat 3-4-5) hurricanes and 201 major hurricane days. By contrast, in a similar 25-year period from 1970-1994 when the globe was undergoing a general warming trend, there were only 38 Atlantic major hurricanes (48% as many) and 63 major hurricane days (31% as many). Atlantic SeaSurfaceTemperatures and hurricane activity do not follow global mean temperature trends.”

Closer to our home here on Anna Maria Island, the historical record of hurricane paths over the last 90 years looks like trending to lower landfalls, but odds are still high.

Major hurricane landfalls

“We believe that the Atlantic basin remains in an active hurricane cycle associated with a strong THC (thermohaline circulation). This active cycle is expected to continue for another decade or two at which time we should enter a quieter Atlantic major hurricane period like we experienced during the quarter-century periods of 1970-1994 and 1901-1925.”

See the full report here.

Leave a Reply