Dr. Bill Gray's final 2006 forecast issued

The tropical Atlantic is quiet today. The computer models are indicating some development is possible early next week in the region between the Bahamas and Bermuda, but this is likely to be extratropical in nature.

Latest hurricane forecast by Dr. Bill Gray
The final 2006 seasonal forecast for the Atlantic hurricane season by the Colorado State University team led by Dr. Bill Gray and Phil Klotzbach was issued yesterday. The new forecast calls for two named storms in October, one of which is a hurricane, which is not expected to be intense. Gray's team forecasts no named storms for November, noting that November tropical cyclones are rare in the Atlantic during El Ni�o events. The average level of October activity is 1.6 named storms and 1.1 hurricanes. These averages decline by about 1/3 in El Ni�o years, to 1.3 named storms and 0.7 hurricanes. No intense (or major) hurricanes have been observed to form after 1 October in El Ni�o years since 1950. Dr Gray's team gives the following odds for landfalls along the U.S. coast in October 2006:

Named storm: 22%
Hurricane: 14%
Intense hurricane: 4%

The average probabilities of landfalling October tropical cyclones in the U.S. the past 52 years looked like this:

Named storm: 29%
Hurricane: 15%
Intense hurricane: 6%

The authors note that the failure of the El Ni�o prediction models to properly forecast the rapidly developing El Ni�o event this year was a major reason why their earlier hurricane forecasts were inaccurate. August-September 2006 sea surface temperatures in Equatorial Eastern Pacific warmed by approximately 0.6�C from their June-July values, which is the greatest increase ever observed in a year that wasn't already seeing an El Ni�o event (the increase was 0.9�C during strongest El Ni�o on record, in 1997; however, 1997 was already a strong El Ni�o event by the beginning of the summer).

I posted my October hurricane outlook yesterday, which calls for just one named storm for the Atlantic the remainder of hurricane season.

Jeff Masters