Storms packed punch, but coast was lucky

Posted on 01 November 2010 Written by Jim Flannery
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In this summer's hurricane crap shoot, people who live along the Eastern Seaboard rolled twice and won, as Danielle and Earl - two powerful late-summer Category 4 hurricanes - slid up the Atlantic coast without making landfall.

"We were lucky," says meteorologist Chris Bedford, founder of Sailing Weather Service (www.sailwx.com), a Boston-based outfit for racing sailors. "Earl came very close to becoming the worst-case scenario for North Carolina."

The Outer Banks had some road overwash from Earl and there was flooding in Ocracoke, Hatteras and other villages. Winds were reported to be 70 to 80 mph as the storm skirted the barrier islands Sept. 3. Earl skirted New England as a 70-mph tropical storm, causing localized flooding.

Had the hurricane remained a 140-mph behemoth and churned up Pamlico Sound, it would have lashed the Outer Banks with a wall of wind from its stronger eastern side and pushed the sound up over the islands, causing catastrophic damage. Instead, Earl stayed 85 miles offshore and weakened to a 105-mph Category 2 storm, as a southwesterly wind shear tore into it and a second eye wall formed. "It was just dumb luck," Bedford says.

Hurricane Danielle, which reached wind speeds of 135 mph, stayed 355 miles east of Bermuda and also weakened to 105 mph as it hooked east farther into the Atlantic. Both storms marched up the East Coast in late August and early September. Bedford says steering currents from troughs rolling off the East Coast and a ridge of high pressure farther out in the Atlantic guided the two hurricanes up but offshore of the coast.

"There has been a general pattern of troughs out in the Atlantic off the East Coast," he says. The timing of those troughs moving out of the Midwest was just right to push the storms offshore. A little different timing and Danielle would have slammed Bermuda and Earl would have battered North Carolina.

As fall settles in, Bedford expects weather patterns off the Atlantic coast to change more frequently - every couple of days instead of every five to seven days - and leave the coast vulnerable to hurricane landfalls. "There's no magic wall sitting out there that keeps the hurricanes from coming ashore," he says. "The important thing to remember is your day is coming. It may not be today. It may not be tomorrow. It may not be 100 years from now. But it behooves us to remember that a storm is coming." Be prepared, he says.

As expected, La NiƱa - cooler waters in the eastern equatorial Pacific - set in this summer, decreasing wind shear over the Atlantic basin and increasing the likelihood of hurricanes developing from depressions forming off western Africa and rolling west across the Atlantic. Sea surface temperatures in the tropical Atlantic this summer were high, as much as 4 F above average in some areas, which also contributed to hurricane formation, says Bedford.

NOAA was predicting 14 to 20 named storms during this June 1 to Nov. 30 hurricane season, eight to 12 of them hurricanes with winds 74 mph or greater and four to six of them major hurricanes of 111 mph or higher. By early September, the Atlantic and Caribbean had spawned 11 named storms, three of them hurricanes and two of them - Danielle and Earl - Category 4s.

"We have a saying around our office," Bedford says. "Bad weather is good for business. Business has been pretty good this year."

This article originally appeared in the November 2010 issue.