The Most Powerful Storms

Posted: September 14, 2004

A little bit slower than a race car at Daytona, those are the winds that make up Hurricane Ivan.

Weather experts have tracked Ivan, with sustained winds of 160 m.p.h. - and gusts reaching 195 - but that's by radar and by airplane, said Michael P. Gaus, president of the American Association of Wind Engineers.

"Scientists have a really hard time measuring wind on the ground because their instruments blow away or the electricity goes off and they stop working," Gaus said. "The engineers are very frustrated."

But even if Ivan's wind speeds at ground level drop 10 m.p.h., it will remain a Category 5 hurricane, which doesn't leave much in its path. Forget stop signs and light poles; facing 150 m.p.h. winds, small buildings will crumple.

The last two hurricanes to hit Florida - Charley and Frances - were Category 4 and 2 storms, respectively.

In 1969, an engineer named Herbert Saffir and Bob Simpson, then director of the National Hurricane Center, developed a wind-to-damage ratio chart.

A Category 1 storm, with winds of 74 to 95 m.p.h., uproots trees and damages mobile homes.

A Category 2 such as Frances, with winds of 96 to 110 m.p.h., causes door, roof and window damage.

A Category 3 hurricane, with winds of 111 to 130 m.p.h., can destroy mobile homes and wreck piers.

Category 4 storms will bring 131-to-155 m.p.h. winds to rip roofs off small houses and cause major beach erosion.

And once you get to a Category 5 storm, with winds above 155 m.p.h., Saffir and Simpson say, the damage is "catastrophic."

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