El Nino weakens, suggesting more 2007 storms

El Nio – which moderated storm activity last year – has dissipated, thereby increasing the likelihood of 2007 being an active season, according to Tropical Storm Risk (TSR), a consortium of experts on seasonal climate forecasting led by the Benfield UCL Hazard Research Centre.

TSR predicts Atlantic basin and U.S. landfalling hurricane activity in 2007 will be about 75% above the 1950-2006 norm, thus upping its previous December 2006 forecast of 60%.

“This is the highest March forecast for activity in any year since the TSR replicated real-time forecasts started in 1984,” TSR announced in a posting on Benfield’s Web site. “It is 86% likely that U.S. landfalling hurricane activity in 2007 will be in the top one-third of years historically.”

The prediction includes:

17 tropical storms for the Atlantic basin as a whole, with nine of these being hurricanes and four intense hurricanes;

Five tropical storm strikes on the U.S., of which two will be hurricanes; and

Two tropical storm strikes on the Caribbean Lesser Antilles, of which one will be a hurricane.

Commenting on the forecast upgrade, TSR lead scientist Mark Saunders said: “The El Nio conditions present since September 2006 dissipated rapidly during February. This has increased the expectation since last month that weak La Nia conditions will occur during the summer.

“As a result, the July to September Caribbean trade wind anomalies are expected to be weaker than thought previously. This factor will increase cyclonic vorticity and cause more storms to be spun up.”