Grandfather wind

data just got better
By Frank Ruggiero
ruggiero@wataugademocrat.com

It’s widely accepted that most everything is high atop Grandfather Mountain.

And now, it’s science fact – at least as far as wind speed is concerned.

In 2006, an anemometer, a device that measures wind speeds, mounted on the Top Shop roof registered a wind gust of 200 miles per hour. Since Grandfather is a cooperative recording station for the National Weather Service, this data raised questions and was contested by the meteorology field, namely due to the anemometer’s location.

Between Linville Peak and Hang Glider Peak, wind is funneled into the area and smack against the Top Shop building and the old anemometer, Grandfather naturalist Gabe Taylor explained. The possibility that these readings were inaccurate became distinct, and Grandfather president Crae Morton became concerned.

“We want to know our weather extremes on the mountain for many reasons,” Morton said. “Of course, it is interesting, but unsafe conditions affect us all, and we need to contribute to the experts’ bank of data.”

A year and a half ago, climatologist and ASU adjunct professor Baker Perry convened a group of experts, comprised of representatives from the National Weather Service and the State Climate Office, as well as a former employee of the National Climatic Data Center.

“I think the general consensus among all parties involved … is that the old anemometer location was just not acceptable,” Perry said. “It didn’t meet really any siting standards that are in place for the National Water Service … and we had been suspicious for quite some time that those wind speeds recorded … were not representative of the wind flow at that general location.

Perry commended Morton for his willingness to work with the scientific community to get to the bottom – or top – of the matter, considering that Grandfather’s reputation was at stake.

In March 2006, Perry and his colleagues visited the mountain to survey potential sites for a new anemometer, with Grandfather staff taking visibility and the viewscape into account. That November, all agreed the best place would be the swinging bridge. The following Februrary, a base was built and welded on to the bridge’s cross arm. Visitors can hardly notice the anemometer, somewhat large but modestly designed, as they approach the bridge.

The device, itself, is an alpine version of a rugged sensor manufactured by R.M. Young, featuring a hydrophobic coating that repels water. Perry said the same model has been wind-tunnel tested to 280 miles per hour, “so it’s a pretty beefy sensor.”

The anemometer records wind gusts at three-second intervals, transmitting the data directly to the collecting center in the neighboring Top Shop. There, manager Thomas Huskins and assistant manager Kyle Barrier gather the data and compare it to that from the old anemometer.

Before jumping to conclusions, Perry said he wishes to gather more data and conduct regression analyses, measuring the relationship between the old and new anemometer, “and I think we’re getting close to having enough data to do that.”

The night of Sunday, Dec. 15, the new anemometer recorded a gust of 98.5 miles per hour, while the old clocked in at 182. Barrier said these differences seem consistent with other recordings, and Morton agrees.

“I could say with great confidence that, from casual observation, the experts were correct,” Morton said. “The higher the wind gusts we see, the greater the difference between the two anemometers we see. The old anemometer was giving inflated wind gust data that did not reflect what was really going on at the top of the mountain.”

Grandfather, so far, has collected about 52 years of data, with the National Weather Service having established a station at the summit in 1955. Too frequently, Huskins recalled, the high winds would tear the device apart, blowing its sensor cups from the rooftop and damaging the wind gauge.

As the device grew more and more outdated, replacement parts became harder to come by, and Huskins was told by the weather service to disregard the project, and the station’s status was downgraded to cooperative recording station.

In the late ’90s, Grandfather purchased commercial measuring equipment and continued to gather data.

“They wouldn’t accept our wind readings, because the anemometer was on the roof, and obstructions were causing the wind to accelerate,” Huskins said. “So, we did it for our own in-house records, because we do have a wind cut-off, as far as allowing the public to come up the mountain.”

Perry said there have been four major wind events since the new device’s installation, as well as smaller gusts, and he is hopeful the analyses can be completed within the next couple of months.

“I think we’re getting close,” he said. “There’s no question it’s a windy, extreme place – a great place to collect data. It’s not been easy for [Grandfather], and I can certainly appreciate that, but I think they’re really trying to do the right thing here, and I have a lot of respect for them.”

Wind speed data can be viewed online at www.grandfather.com/planning_your_visit/weather_conditions.php. For more information, call Grandfather Mountain at (828) 733-2013 or visit www.grandfather.com.