13 to 17 Named Disturbances, Including 7 to 10 Hurricanes, Are Predicted
By Michael E. Ruane
Washington Post Staff Writer
Wednesday, May 23, 2007
Far away, off the coast of South America, the waters of the Pacific Ocean are cooling ominously. In the Atlantic, the sea surface remains warm. And overhead, the atmosphere is evolving toward what forecasters said yesterday could be a dangerous hurricane season.
Experts at the National Oceanic and Atmospheric Administration -- the parent agency of the National Weather Service -- said such factors indicate the 2007 hurricane season could have 13 to 17 named storms, including seven to 10 hurricanes. Of those, three to five could be major hurricanes.
The agency said past data also suggest the possibility of two to four hurricanes making U.S. landfall.
The announcement came in a news conference at Reagan National Airport amid dire warnings from a host of federal government officials about complacency after last year's relatively quiet season, in which no hurricane made landfall on a U.S. coast. It was only the 12th year since 1945 that had no U.S. hurricane landfalls.
"Last year was an unexpectedly easy season," Department of Homeland Security Secretary Michael Chertoff said yesterday. "There's no guarantee that this season is going to be anything less than tough. . . . It is a big mistake to count on being lucky. You're much better off preparing yourself for the worst, and then if you get lucky, that's a bonus."
The NOAA hurricane forecast was the latest this spring to predict a stormy season. An average season has 11 named storms, with six becoming hurricanes and two of those becoming major storms, NOAA said.
Last year had 10 named storms and five hurricanes -- two of which were major, Category 3 or higher, said forecasters at Colorado State University.
In April, Colorado State experts predicted 17 named storms for this year, nine hurricanes and five major hurricanes. The university plans to update its forecast next week, with little change expected.
On May 8, AccuWeather.com, the weather agency based in State College, Pa., predicted 13 or 14 named storms for this year, with three or more Category 3 hurricanes and six or seven storms making U.S. landfall. A day later, the season's first named storm, subtropical system Andrea, formed off the Georgia coast and quickly dissipated.
Forecasters are still smarting from erroneous predictions that much of 2006 would be a busy hurricane season. "Our August-only forecast was a bust," Colorado State's experts said at the end of that season.
They were fooled by the rapid and unforeseen development over the summer of El Niño -- a warming of the water in the Pacific off the coast of South America. Such warming can produce wind conditions over the Atlantic Ocean that are detrimental to hurricane formation.
El Niño is waning, experts said yesterday, and that and other evidence points to this year's forecast.
Gerry Bell, the lead hurricane forecaster with NOAA's Climate Prediction Center, said an "active hurricane era" began in 1995 and is associated with warm Atlantic Ocean surface temperatures.
It is not certain how long the era will last, he said, but others have lasted 25 to 40 years. NOAA forecasters said they are not exactly sure what role global warming might have played in recent active hurricane seasons.
Bell said the transition from the warm Pacific water of El Niño to the cooler water of La Niña -- with the warm water in the Atlantic -- is an indicator of possible trouble.
The El Niño phenomenon tends to produce wind shear, or radical changes in wind direction, in the layers of the atmosphere over the Atlantic, Bell said. Wind shear works against the formation of hurricanes.
La Niña reduces wind shear in the Atlantic and produces more uniform atmospheric wind conditions that are favorable to hurricane formation, he said.
It might seem amazing that water temperature in the Pacific affects the weather in the Atlantic, but as William M. Gray, professor emeritus of atmospheric science at Colorado State, said this week: "The whole atmosphere beats as one unit."
Government officials at the airport said yesterday that they were prepared for a busy storm season. They displayed three Air Force Reserve and NOAA hurricane observation and research airplanes.
They said NOAA would use a new mathematical modeling system this year that would better predict storm tracks. The Air Force Reserve planes were being equipped with a new kind of "radiometer" that calculates surface wind speed by measuring radiation emitted from sea foam, they said.
The Atlantic hurricane season begins June 1, peaks in August and September, and ends Nov. 30.
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