Hurricane Forecast: Heightened Activity For Rest Of Season

The individual month of September and the two-month period of October-November are expected to experience five named storms each. In September, the forecast calls for four of the five storms to become hurricanes and two to become major hurricanes. In October-November, the team forecasts two of the five named storms to become hurricanes and one to become a major hurricane.

"We expect the remainder of the season to be active," said Phil Klotzbach, lead author of the hurricane forecast. "The conditions in the Pacific are transitioning to a weak La Nina.  We have seen low pressure readings in the tropical Atlantic during August. The combination of these two factors usually implies an active season."

"We predict that September-November will exhibit characteristics of an active year based on climate signals through August," said William Gray, who has been issuing hurricane forecasts at Colorado State for 24 years.

These conditions include Atlantic basin sea surface temperatures that have remained at near-normal values along with ENSO conditions that trended slightly cooler during August. Atlantic sea level pressure values were at near-record low levels during August.  

June-July 2007 had average activity with two named storms forming during the two-month period (Barry and Chantal). No activity occurred in the deep tropics during June and July.

August had about average numbers of tropical cyclone formations. The one hurricane that formed (Dean) reached Category 5 status and lasted for 3.75 days as a major hurricane. This is the most days that a single major hurricane has accrued during the month of August since Hurricane Frances in 2004.

The Colorado State team continuously works to improve forecast methodologies based on a variety of climate-related global and regional predictors.