Joining the chorus of other forecasters who have recently warned of a "very active" 2007 Atlantic hurricane season, forecasting network WeatherBug said it is predicting 13 to 15 named storms in the Atlantic, seven to nine of which are expected to develop into hurricanes. Of those hurricanes, three are forecast to become major hurricanes with winds in excess of 111 mph.

Despite the "relative lull" in hurricane activity that occurred in 2006, the forecasting firm said several factors point to a resumption in the recent trend of "active to hyperactive" hurricane activity in the Atlantic in 2007.

After experiencing a weak to moderate El Nino in 2006, a swing to La Nina conditions is expected this summer, WeatherBug said, noting that La Nina is the term used to describe colder-than-normal Pacific Ocean waters near the Equator, while El Nino describes unusually warm Pacific waters.

"Whereas El Nino episodes tend to produce winds that rip apart Atlantic tropical systems, La Nina is associated with weaker westerly wind flow that does not hinder tropical storm formation," WeatherBug said. "Historically, weak and moderate La Nina conditions have resulted in above-average hurricane activity; this is especially true the year after an El Nino episode."

The north Atlantic as a whole continues to experience abnormally warm sea-surface temperatures. "A hyperactive hurricane season falls in line with the cycle occurring in the Atlantic for the past 10 years," said Michael Whitehead, WeatherBug's principal energy meteorologist.

Forecasts over the last month from Tropical Storm Risk (TSR), AccuWeather and the Colorado State University (CSU) hurricane forecast team led by Phil Klotzbach and William Gray have all called for more active than normal storm activity this year. London-based TSR is forecasting 2007 Atlantic basin and U.S. landfalling tropical cyclone activity will be about 75% above the 1950-2006 norm, the highest March forecast for activity in any year since the forecaster began issuing real-time forecasts in 1984 (see Daily GPI, March 22).

While AccuWeather's full hurricane forecast is set to be released in conjunction with the second annual AccuWeather Hurricane Summit in Houston in early May, the forecasting firm's chief hurricane forecaster Joe Bastardi has been issuing sneak peeks over the last month (see Daily GPI, March 28). Bastardi warned that the U.S. Gulf Coast, which avoided the wrath of major storms and hurricanes in 2006, is at much higher risk of destructive tropical weather this year. And in the Atlantic, the Northeast also could suffer some hits.

Upping its December prediction, the CSU team has said the U.S. Atlantic basin will likely experience a very active hurricane season in 2007 with an increased probability of a major hurricane making U.S. landfall (see Daily GPI, April 4). The news surprised many within the energy industry who had expected that the team's April forecast would simply be a rehash of its December 2006 outlook (see Daily GPI, March 29).

The CSU team's forecast now anticipates 17 named storms forming in the Atlantic Basin between June 1 and Nov. 30, with nine of the 17 storms expected to become hurricanes, and of those nine, five are expected to develop into intense or major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater. The team's first extended-range forecast released in December anticipated 14 named storms forming in the Atlantic Basin between June 1 and Nov. 30, with seven of the 14 storms predicted to become hurricanes, and of those seven, three were expected to develop into intense or major hurricanes.

The 2006 season witnessed a total of 10 named storms, five hurricanes and two major hurricanes, while the 2005 season witnessed 27 named storms, 15 hurricanes and seven intense hurricanes. Long-term averages are 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes per year.

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