With the official start to the 2007 Atlantic hurricane season beginning, the energy industry on Thursday received no last-minute reprieve from the recent forecasts calling for an active season.
Colorado State University (CSU) hurricane forecasters on Thursday maintained an earlier forecast that called for a very active 2007 season with a 74% chance of a major hurricane making landfall on the U.S. coastline, with the Gulf of Mexico coast and Florida exceptionally vulnerable (see Daily GPI, April 4).
The hurricane forecast team headed by CSU's Phil Klotzbach and William Gray is still calling for 17 named storms forming in the Atlantic basin between June 1 and Nov. 30. Nine of the storms are expected to become hurricanes with five becoming intense hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.
No hurricanes made landfall along the U.S. coastline in 2006. The 2006 season witnessed a total of 10 named storms, five hurricanes and two major hurricanes. Long-term averages are 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes per year. Forecasters across the globe over the last couple of months have unanimously forecasted an active 2007 hurricane season with a high probability of U.S. landfall (see Daily GPI, May 23).
"We expect an above-average hurricane season with ENSO [El Nino/southern oscillation] conditions on the cool side, which will help increase the likelihood of major storm activity in the Atlantic," said Klotzbach. "El Nino conditions during the summer and fall -- similar to those that developed in 2006 -- tend to decrease Atlantic hurricane activity by increasing vertical wind shear across the area where Atlantic tropical cyclones develop."
The hurricane forecast team predicts tropical cyclone activity in 2007 will be 185% of the average season. By comparison, 2005 witnessed tropical cyclone activity that was about 275% of the average season.
The hurricane forecast team reiterated its probabilities for a major hurricane making landfall on U.S. soil:
The team also predicted above-average major hurricane landfall risk in the Caribbean.
The 2006 season was only the 12th year since 1945 that the United States experienced no hurricane landfalls. Since then there have been only two consecutive-year periods where there were no hurricane landfalls: 1981-1982 and 2000-2001.
"There were a lot of challenges in 2006 that we didn't expect, such as a late-developing El Nino, which causes increased vertical wind shear and results in less tropical cyclone activity," said Gray, who began forecasting hurricane seasons at CSU 24 years ago.
For 2007, Klotzbach and Gray expect continued warm tropical and north Atlantic sea-surface temperatures, prevalent in most years since 1995, as well as neutral or weak La Nina conditions -- a recipe for greatly enhanced Atlantic basin hurricane activity. The forecasters noted that these factors are similar to conditions that occurred during the 1952, 1954, 1964, 1966, 1995 and 2003 seasons. The average of these six seasons had well above-average activity, and Klotzbach and Gray predict the 2007 season will have activity in line with the average of these six years.
"We are in a new era for storms that is part of a natural cycle," Gray said. "We've had an upturn of major storms in the Atlantic since 1995. This active cycle is expected to continue for another decade or two at which time we should enter a quieter Atlantic major hurricane period like we experienced during the quarter century periods of 1970-1994 and 1901-1925. These changes in storm activity are not caused by human-induced global warming but by natural forces."
The CSU team has said the hurricane seasons of 2004 and 2005 were anomalies: Florida and the Gulf Coast were ravaged by four landfalling hurricanes each year. Hurricanes Charley, Frances, Ivan and Jeanne caused devastating damage in 2004 followed by Dennis, Katrina, Rita and Wilma in 2005.
The team said it will issue seasonal updates of its 2007 Atlantic basin hurricane activity forecast on Aug. 3, Sept. 4 and Oct. 2, which will each include separate forecasts for each of those months.
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