Climatology shows that the peak for tropical cyclone activity in the Atlantic is the second week in September.
Number of Atlantic basin tropical storms and hurricanes per 100 years (courtesy NOAA)
Drs. Phil Klotzbach and Bill Gray are predicting Atlantic hurricane activity from September 5 to September 19, 2009 ”will be characterized by reduced amounts (70 percent or less) of activity relative to climatology” based on a combination of observational and modeling tools.
Dr. Bill Gray is regarded as the pioneer in seasonal hurricane forecasting and has been making seasonal hurricane forecasts since 1984. Dr. Phil Klotzbach joined Bill Gray’s forecast team in 2001. This year, in addition to providing seasonal forecasts, Dr. Klotzbach and Gray started making 15-day forecasts near the beginning of August.
Some people will ask if these new 15-day forecasts have any value. In response, I would ask how one knows if they have value unless someone makes and verifies the forecasts. I have always appreciated the way Bill and Phil publish their forecasts and provide easy access to the verifications of the forecasts. Of course, there are a lot of other reasons that I tip my hat to Bill and Phil. They have both already left their marks on tropical meteorology. Bill Gray has done this over a period of several decades and continues to do so by working on synthesizing his many years of hurricane studies and by studying global warming issues. Phil Klotzbach is a fairly recent Ph.D. graduate, and, in my opinion, will continue making significant contributions to tropical meteorology for decades to come.
The recent Klotzbach/Gray forecast as well as past forecasts and verifications are available online at http://hurricane.atmos.colostate.edu/Forecasts.
Max Mayfield's Hurricane Blog 