Bleak forecast for 2007 hurricane season

Benfield's Tropical Storm Risk (TSR) has increased its forecast for the Atlantic hurricane activity in 2007. Based on current and projected climate signals, TSR's March forecast predicts Atlantic basin and US landfalling hurricane activity to be about 75% above the 1950-2006 norm in 2007, rising from 60% above norm (TSR long-range forecast issued December 2006). This is the highest March forecast for activity in any year since the TSR replicated real-time forecasts started in 1984.According to TSR, it is 86% likely that US landfalling hurricane activity in 2007 will be in the top one-third of years historically. The prediction includes:

• A 86% probability of an above-normal Atlantic hurricane season, a 11% probability of a near-normal season and only a 3% chance of a below-normal season;
• 17 tropical storms for the Atlantic basin as a whole, with nine of these being hurricanes and four intense hurricanes;
• A 85% probability of above-normal US landfalling hurricane activity, a 12% likelihood of a near-normal season and only a 2% chance of a below-normal season;
• Five tropical storm strikes on the US, 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, Professor Mark Saunders, the TSR lead scientist and head of weather and climate extremes at the Benfield UCL Hazard Research Centre at University College London said: “The El Niño conditions present since September 2006 dissipated rapidly during February. This has increased the expectation since last month that weak La Niña 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. The sudden El Niño dissipation is the main reason for the TSR forecast for hurricane activity in 2007 rising from 60% above-norm in our long-range forecast last December, and also in our January and February updates to 75% above-norm in our March forecast.”