Prediction Group Sees Revved-Up U.S. Storm Action

A London-based forecasting group is predicting increased storm activity this year with two hurricanes hitting the United States.

Tropical Storm Risk (TSR), a brokerage-backed consortium, said the more active season is likely because El Ni?o, which moderated storm activity last year, has dissipated.

Benfield UCL Hazard Research Centre at University College London said it increased its forecast for Atlantic hurricane activity based on current and projected climate signals.

For March, TSR, based at the college, predicts Atlantic basin and U.S. landfalling hurricane activity will be about 75 percent above the 1950-2006 level.

This is an increase from 60 percent above norm, which was the TSR long-range forecast issued December 2006.

The consortium said 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 percent likely that U.S. landfalling hurricane activity in 2007 will be in the top one-third of years historically.

The prediction includes:

o An 86 percent probability of an above-normal Atlantic hurricane season, an 11 percent probability of a near-normal season, and only a 3 percent chance of a below-normal season.

o Seventeen tropical storms for the Atlantic basin as a whole, with nine of these being hurricanes and four intense hurricanes.

o An 85 percent probability of above-normal U.S. landfalling hurricane activity, a 12 percent likelihood of a near-normal season, and only a 2 percent chance of a below-normal season.

o 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.

TSR said two climate factors influence the forecast. One is the expected August and September trade wind speeds, which blow westward across the tropical Atlantic and Caribbean Sea and influence spinning up of storms.

The second is the sea temperature between West Africa and the Caribbean, which provides heat and moisture to power incipient storms.

Professor Mark Saunders, TSR lead scientist and head of Weather and Climate Extremes at the Benfield UCL Hazard Research Centre, said the El Ni?o conditions present since September 2006 dissipated rapidly during February, increasing the expectation that weak La Ni?a 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," he said.

TSR said it will issue a forecast update in April. TSR forecasts are online at www.tropicalstormrisk.com.