Tornado to Be 1st Assessed by New Scale

The Associated Press
Friday, February 2, 2007; 8:38 PM

NORMAN, Okla. -- A tornado that devastated central Florida will be the first categorized under a scale that went into effect Thursday, weather officials said.

The timing is "just coincidental," said Keli Tarp, spokeswoman at the federal government's Storm Prediction Center in Norman.

The National Weather Service had already announced it was changing the Fujita Scale, a 35-year-old system of ranking a tornado's strength, to align wind speeds more closely with actual damage.

Under the old system, an F-5 tornado _ considered the most powerful of tornadoes _ was capable of destroying a typical frame house, with wind speeds estimated at 261 mph to 318 mph. Since then, engineering studies have shown that much slower winds could cause the same damage.

A tornado rating a 5 on the Enhanced Fujita scale has winds of more than 200 mph, under the scale that took effect Thursday.

It's nearly impossible to know the true wind speed at ground level, according to the weather service's Web site. The Enhanced scale is a set of wind estimates _ not measurements _ based on damage.

"It is a way to be more accurate and consistent," Tarp said of the new scale.

The Florida storm has not been assessed yet, Tarp said. The local weather service office makes that determination, and it could take several days.

James LaDue, a weather service meteorologist who helped create the Enhanced Fujita scale, flew from Norman to central Florida on Friday to assist the local office.

Storms including at least one tornado killed several people and destroyed hundreds of homes in central Florida just before daybreak Friday.

© 2007 The Associated Press