As Tropical Storm Chris continued to weaken just north of Puerto Rico (see related story), the 2006 Atlantic hurricane season was dealt an additional blow Thursday morning as respected hurricane forecasters William Gray and Philip Klotzbach of the Colorado State University (CSU) hurricane forecast team issued a report reducing the number of storms expected in the basin this season.

In late May (see Daily GPI, June 1), Klotzbach and Gray had called for 17 named storms, nine hurricanes and five intense hurricanes (Saffir/Simpson category 3-4-5). Their revised forecast calls for a total of 15 named storms, seven hurricanes and three intense hurricanes.

However, the researchers warned that that their revised forecast is still calling for above-average hurricane activity this year and they expect above-average tropical cyclone activity in August and September. That’s despite an average start to the season with two named tropical storms forming in June and July. The long-term average for activity during a season is 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes per year.

“We’re not reducing the number of hurricanes because we had only two named storms through late July,” Gray said. “It’s a general erosion of a number of factors. The tropical Atlantic sea surface temperatures are not quite as warm, tropical Atlantic surface pressure is not quite as low, the eastern equatorial Pacific has warmed some and trade winds in the tropical Atlantic are slightly stronger.”

Klotzbach said he believes the East Coast is in more danger this year from hurricanes than the Gulf Coast. “Overall, we think the 2006 Atlantic basin tropical storm season will be somewhat active and about 140% of the long-term average,” said Klotzbach. “This year it looks like the East Coast is more likely to be targeted by Atlantic basin hurricanes than the Gulf Coast, although the possibility exists that any point along the U.S. coast could be affected by a hurricane this year.”

In updating its Landfall Probability web site (www.e-transit.org/hurricane), the team said it continues to warn of the considerably greater-than-average probability of at least one intense (or major) hurricane making landfall in the United States this year. According to the latest forecast, there is a 73% chance of an intense hurricane hitting somewhere along the U.S. coastline in 2006 (long-term average is 52% according to the CSU team). For the U.S. East Coast, including the Florida Peninsula, the probability of an intense hurricane making landfall is 64% (long-term average is 31%). For the Gulf Coast from the Florida Panhandle westward to Brownsville, TX, the probability is 26% (the long-term average is 30%).

Gray remarked that the United States has been “fortunate” over the past few decades in experiencing only a few major hurricanes making landfall in Florida and along the East Coast. Between 1995 and 2003, 122 named storms, 69 hurricanes and 32 major hurricanes formed in the Atlantic basin, he said. During that period, only three of the 32 major hurricanes — Opal, Bret and Fran — crossed the U.S. coastline. Based on historical averages, about one in three major hurricanes comes ashore in the United States.

However, over the past two years 13 major hurricanes formed in the Atlantic basin — seven of them striking the U.S. coast. Gray noted that Florida and the Gulf Coast were ravaged by four landfalling hurricanes in each of the past two years: In 2004, Hurricanes Charley, Frances, Ivan and Jeanne caused devastating damage followed in 2005 by Dennis, Katrina, Rita and Wilma.

“Last year was an anomaly — for many years, we’re going to be studying why last year was such a freak year,” Gray said. “We’re in this active cycle in the Atlantic basin that is expected to last another 15 to 20 years. There’s no evidence that storms have gotten worse because the globe has warmed. Unfortunately, with the large coastal population growth in recent decades, we need to anticipate hurricane-spawned destruction in coming years on a scale many times greater than what we have seen in the past.”

Breaking down the remaining months of the season separately, the CSU team said it expects August to contain four named storms, three hurricanes and one intense hurricane for the Atlantic basin. For September, the team predicts five named storms, three hurricanes and two intense hurricanes. For October, the researchers predict two named storms, one hurricane and no intense hurricanes.

“The same factors that make individual months active or inactive are often not the same factors that can make the entire season active or inactive,” said Klotzbach. “We are continually improving our forecasts to provide people with specific monthly hurricane forecasts and specific landfall probability forecasts.”

The team said it will issue seasonal updates of the 2006 Atlantic basin hurricane activity on Sept. 1 and Oct. 3.

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