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Blowing in the Wind

Professor searches for answers where tornadoes touched down in the mountains

By Graham Averill

Godfrey

IN THE STORM’S WAKE: Above, Godfrey stands on a hillside that used to be a lush forest before the EF3 tornado passed over.

STANDING ON THE LOOKOUT ROCK
Observation Tower near the western edge
of Great Smoky Mountains National Park,
you can still see the tornado's path—a
long line of downed trees tossed over like
Pick Up Sticks. The winds that accompanied the tornado that swept through on April 27, 2011, are thought to have reached up to 170 mph—that's an EF4
on the Enhanced Fujita rating scale—and
left a flat spot a quarter-mile wide and 13
miles long. It's the first tornado known
to have hit the park, challenging the longstanding notion that tornadoes don't occur in the mountains.

“That’s a commonly held myth, but tornadoes absolutely do happen in the mountains,” says Christopher Godfrey, a professor of Atmospheric Sciences at UNC Asheville. “Tornadoes may occur less frequently in the mountains than in other parts of the state, but they still pose a very real threat.”

Godfrey and Chris Peterson, a forest ecologist from University of Georgia, received a National Science Foundation grant to study the Smokies tornado and another that hit Georgia’s Chattahoochee National Forest, both of which were part of a rash of hundreds of tornadoes that formed in the Southeast on the same day. With his research project, titled “Reconstruction of Near-Surface Tornado Wind Fields from Forest Damage Patterns in Complex Terrain,” Godfrey is studying the fall pattern of trees downed in the tornado through aerial photos and ground surveys. Back on campus, Michael Goldsbury, an Atmospheric Sciences senior, is entering data into GIS software that flags the direction of trees that fell in sample areas.

The goal is to learn how mountainous terrain affects the wind field of tornadoes and understand more about near-surface conditions, particularly wind speed, during a storm.
“Both of these tornadoes went up and down mountains. They went over lakes, across rivers. They did all of the things people assume tornadoes can’t do. There’s still a lot we don’t know about tornadoes,” Godfrey says.

Godfrey hopes the tree damage data will give the National Weather Service a better understanding of how tornadoes behave in mountainous terrain by deter­mining what wind speeds affect which tree species.

“Since we don’t know how these violent winds impact different tree species, the weather service uses indicators at nearby developed locations to rate these remote storms,” Godfrey says. “The tornado in the Smokies earned an EF4 because it destroyed a single electrical tower in a lake near the park, but it could have been a much stronger storm where it hit in the mountains.”

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