NOAA expects 'active' hurricane season

14 to 23 named storms possible

May 27, 2010|By Frank D. Roylance, The Baltimore Sun

All the key factors of ocean and atmosphere are falling into place for what federal forecasters say will be an "active to extremely active" Atlantic hurricane season.

It could become "one of the more active on record," said Gerry Bell, lead seasonal hurricane forecaster at NOAA's Climate Prediction Center. The federal agency announced its 2010 hurricane forecast on Thursday.

Officials say the season's threat will be complicated this year by the huge oil slick in the Gulf of Mexico. Storm surges could push the spreading crude far inland.

The storm forecasters said there is a 70 percent chance the Atlantic basin will see 14 to 23 named storms before the season ends Dec. 1.

Of those storms, the National Oceanic and Atmospheric Administration predicts eight to 14 will reach hurricane force, and three to seven could become "major" storms, with Category 3 winds of 111 mph or more.

These seasonal outlooks never include predictions of where the storms are most likely to strike land. But "if the season is extremely active, that's when there is the highest likelihood of hurricane strikes on both [the Atlantic and Gulf] coasts," Bell said. "In fact, multiple strikes on both coasts."

"That's not a forecast," he said. "It's historically what we've seen."

And that reality should be enough to spur residents in those regions to prepare. "Gulf Coast and East Coast residents … should be preparing for any hurricane season," he said. "Complacency and hurricanes do not mix. Your first line of defense is you. It's not the government."

The May hurricane outlook from NOAA follows similar predictions from other organizations.

Two weeks ago AccuWeather.com predicted a 2010 season with 17 named storms, 10 hurricanes and four "major" storms. A team at Colorado State University in April predicted 15 named storms and eight hurricanes, four of them major.

Everyone is basing their predictions on the same basic factors of air and ocean that appear to be falling together this summer. They include:

•The end of the El Nino event — a warm phase in the cycle of surface water temperatures in the tropical Pacific that helped to suppress tropical storm formation in the Atlantic during the 2009 season.

•The likelihood that El Nino will be replaced this summer by a La Nina event — the cool phase of the same cycle. La Nina events tend to reduce the kind of wind patterns that cut off Atlantic storm development.

•Record high sea surface temperatures in the Atlantic, where many of the storms develop — up to 4 degrees Fahrenheit above average.

•Continuation of a cycle of Atlantic air pressure and water temperature patterns, favorable for storm formation, that began in 1995.

"The main uncertainty in this outlook is how much above normal the season will be," Bell said.

"Whether or not we approach the high end of the predicted ranges depends partly on whether or not La Nina develops this summer." On that score, he added, "Conditions are becoming increasingly favorable for La Nina to develop."

Bell said the Pacific Ocean is now in a "neutral" phase, but surface temperatures in the equatorial Pacific are dropping, a deep layer of cold water is also being established and trade winds are strengthening.

Whether it becomes a weak or a strong La Nina does not seem to matter, Bell said. "Even a weak to moderate La Nina can affect winds over the Atlantic."

"There is quite a high confidence in this forecast, as opposed to last year, when we said there was a lot of uncertainty in that outlook," he said.

All the hurricane forecasters overestimated last spring the number of named storms the 2009 season would produce. As El Nino developed during the summer, predictions were revised downward, and the season ended slightly below average, with nine named storms and three hurricanes.

But Bell defended his agency's work, saying its May forecasts have been "correct" for seven of the past 11 hurricane seasons.

By "correct," he said, he doesn't mean getting the storm count exactly right, but rather that his center accurately predicted whether the season would be average, below average or above average.

But Bell insisted the precision of the forecast is less important now than getting the message out that people in hurricane-prone parts of the country be prepared for any storm season.

"Regardless of this outlook," he said, "all it takes is one hurricane to strike your area."

Officials were unable to predict the risk that this season's storms would cross the island of Haiti, where large portions of the population continue to live in makeshift camps in the wake of last winter's devastating earthquake.

They did say storms striking in the Gulf of Mexico could be expected to push some of the oil from the BP well disaster inland. Just where it goes ashore will depend on the hurricane track.

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