NEW YORK, (Dow Jones Newswires), Aug 03, 2007 (Dow Jones Commodities News)
The current Atlantic hurricane season will show above normal activity, but with two fewer storms and one less hurricane than earlier predicted, widely-watched forecasters at Colorado State University said in a report Friday.
In an update to a pre-season forecast, meteorologists trimmed their expectations for the June 1-Nov. 30 season, but said the season will be "much more active" than the 50-year average.
They expect 15 named storms, 8 hurricanes and 4 intense hurricanes.
The forecasters had predicted on May 31 that the 2007 season would feature 17 named storms, 9 hurricanes and 5 intense hurricanes with sustained winds of 111 miles per hour or more. The 50-year average is 9.6 named storms, 5.9 hurricanes and 2.3 major hurricanes.
Forecasters also slightly lowered the assessment of the likelihood of a major hurricane making landfall somewhere in the U.S. to 68% from the earlier 74%. The revised forecast is still above the long-term probability of 52%.
Forecasters said "slightly cooler sea surface temperatures over the tropical Atlantic" led to the downward revision in the expected storm count.
In August, the forecasters expect three named storms, two hurricanes and one intense hurricane in the Atlantic basin.
For September, five named storms are predicted, including four hurricanes and two intense hurricanes.
For October and November, five named storms, two hurricanes and one intense hurricane are expected.
In the Gulf Coast region, stretching from the Florida Panhandle to Brownsville, Texas - housing many of the nation's oil refineries - the probability of an intense hurricane making landfall is 44%, compared with 30% long-term, but down from 49% in the earlier forecast.
East Coast Odds Reduced
Forecasters said the probability of an intense hurricane making landfall along the East Coast, including the Florida peninsula, is 43% this season, compared with the long-term probability of 31%. That's a reduction, though, from a 50% probability in the earlier forecast.
Researchers Philip Klotzbach and William Gray said only two named storms have been observed so far this season, adding they don't include subtropical storm Andrea, which formed off the southeastern U.S. on May 9 and was never classified as a tropical storm by the National Hurricane Center.
"The number of storms that formed during June and July isn't relevant to this newest forecast," Klotzbach said. "We've lowered our forecast from our May predictions because of slightly less favorable conditions in the tropical Atlantic." He said sea surface temperature anomalies have cooled across the area in recent weeks, "and there have been several significant dust outbreaks from Africa, signifying a generally stable air mass over the tropical Atlantic."
Last year, high levels of atmospheric dust from Africa played a part in altering conditions for what was expected to be an unusually active hurricane season. The season turned out to be mild relative to historical levels.
Forecasters said they expect generally cool to weak La Nina conditions to be present during the season. La Nina is the name given to the unusual cooling of water temperatures in the equatorial Pacific Ocean.
Gray said the presence of La Nina conditions will likely keep this year's hurricane season active until its end-November conclusion.
Historical data from the National Hurricane Center show that since 1851 only 16 of 96 hurricanes that hit the U.S. mainland occurred in October, most of them in southern Florida. Only 6 major hurricanes have formed in the U.S., Caribbean and Gulf of Mexico area in November since 1851, five of those in the U.S., and only three in the region since 1966, according to the NHC.
Active Cycle Continues
In the Gulf of Mexico region, 91% of all major hurricanes have taken place between August and October, according to forecasters at Weather 2000.
Colorado State forecasters also see above-average risk of hurricanes making landfall in the Caribbean.
Gray said active hurricane seasons are likely to be the norm in coming years.
"We're in an active cycle in the Atlantic Basin that is expected to last another 15 to 20 years," he said. "We believe this is part of a natural ocean cycle and is not the result of human-induced global warming."
The forecasters will update their hurricane predictions on Sept. 4.
The federal National Oceanic and Atmospheric Administration said May 22 it sees a 75% chance that the 2007 hurricane season will show above normal activity. NOAA predicted 13-17 named storms, 7-10 hurricanes and 3-5 major hurricanes.
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