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Recent winds hit area hard

June 21, 2004|by BRIAN SHAPPELL

shappell@herald-mail.com

WASHINGTON COUNTY - Uprooted trees, branches strewn about and scattered debris are among the post-thunderstorm messes that lead many to believe their area was hit by a tornado, National Weather Service spokespeople said.

But in most cases, like early last week in the Boonsboro area, the people reporting tornadoes to the weather service often misidentify what are a more damaging occurrence, straight-line winds, they said.

Cindy Woods, a National Weather Service meteorologist, said damaging winds accompanying thunderstorms are either tornadoes or straight-line winds. Straight-line winds, which exceed 58 mph, notably push over trees in one direction. That differs from a tornado's impact on trees, which are twisted and "tossed around more" than they are by straight-line winds, Woods said.

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Tornadoes, characterized by their swirling winds, are broken into six classifications, starting with an F0 with winds of 40 to 74 mph. The strongest tornadoes, classified as F5s, carry winds exceeding 261 mph, Woods said.

Woods said straight-line winds and tornadoes can substantially damage an area in a short amount of time.

"Whether it fell because the wind pushed it one way or it was twisted up in a tornado, you're still in pretty bad shape," she said.

Last Tuesday, a violent thunderstorm brought powerful winds that uprooted trees in and near Boonsboro. Among the hardest-hit places were Shafer Memorial Park and St. Mark's Episcopal Church, which is on Lappans Road.

The damage was a result of straight-line winds, not a tornado, said David Manning, a warning coordination meteorologist for the National Weather Service. Many in the area reported that a tornado hit the area, he said.

Manning said a tornado touched down in the Leitersburg area May 25, though an AccuWeather meteorologist said the tornado hit west of Thurmont, Md., not in Washington County. Approximately 4,100 Allegheny Power customers were without power in Washington County as a result of the thunderstorm and accompanying winds.

Manning, who investigates the accuracy of tornado reports, said most cases involving damage during a thunderstorm are attributable to straight-line winds rather than their more well-known counterpart.

Manning said fewer than 10 percent of all thunderstorms produce damaging winds and less than 1 percent produce tornados.

Manning also said straight-line winds usually do more damage than tornadoes because they span a greater distance.

"Tornadoes are a small entity. An F1 can be as small as a couple hundred yards wide," Manning said. "Straight-line winds can go for miles."

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