Mountain wave sparked Gatlinburg wildfires, May 4 destruction

“The winds that blow through the wide sky in these mountains, the winds that sweep from Canada to Mexico, from the Pacific to the Atlantic – have always blown on free men.”

The words are those of former President Franklin Delano Roosevelt, ending his speech at the dedication of Great Smoky Mountains National Park on Sept. 2, 1940.

Winds are nothing new to the Smoky Mountains. John Oliver made sure when he built his cabin home in Cades Cove in the 1820s to use strong timber and pack the mud chinking in solidly to protect his house against strong winds.

Throughout history are stories of wind events that have caused major, sometimes deadly damage in the Smokies.

A windstorm on July 5, 2012 killed two people in the Smokies. Then, winds of nearly 60 mph raced through the park in a weather event called a derecho. A derecho, as National Weather Service meteorologist Derek Eisentrout said at the time, is an organized area of thunderstorms that fall into a squall line – a long-lived, straight-line wind storm.

Lately, the legendary winds of the Smokies have again been up to no good.

The wildfire that killed 14 people and raged through 17,000-plus acres of the park on Nov. 28 would likely have amounted to very little without the 90 mph wind that turned a 1.5-acre fire five miles into the park woods at Chimney Tops 2 fire into the massive blaze that damaged or destroyed more than 2,400 structures in the Gatlinburg area. A months-long drought also played a big role.

Then on Thursday, May 4, another wind dashed through with gusts clocked at nearly 100 mph at some places like Chalet Village in the mountains overlooking the city. It blew over or damaged homes just getting rebuilt after being burned to the ground on Nov. 28. More than 15,000 customers were without electric power.

Numerous roads in the park were closed as well as the visitor centers and other buildings. On Monday, Cherokee Orchard Road, Roaring Fork Motor Trail, West Cove Gap and the Greenbrier Entrance Road were still closed.

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Guardrails on the Gatlinburg Bypasss were damaged as was the roof at Park Headquarters next to Sugarlands Visitor Center and Smith Cabin in the Daisytown part of the Elkmont historic area.

Crews were also working to clear debris on various trails although none are closed at present because of damage from Thursday’s event; some are still closed from damage caused by the Nov. 28 fire.

Mountain wave

These winds were not a derecho but something called a mountain wave.

Andrew Pritchett, a meteorologist with the NWS in Morristown, explained that when a low pressure system moves into a mountainous area, it sometimes bangs off more stable air above and bounces down at greater velocity.

“It’s like a basketball bouncing off a ceiling and shooting back down,” Pritchett said. “You get these winds that hit that stable air then bounce back down over the mountains. Because of the shape of the terrain and the meteorology that is in place up in the atmosphere you can get these high wind incidents.

“It’s like a big puzzle with each piece contributing to a more intense wind than it should be.”

Thursday's culprit was a massive storm that had dumped more than a foot of water along the Mississippi River, causing flooding around St. Louis and elsewhere. That system knocked up against stable air over the Smokies and the wind was off to the races.

Jim Renfro, air quality specialist with the Great Smoky Mountains National Park, said there is a twist to it all.

"When you have a high low pressure system like the one Thursday from the west, it will often be accompanied by a strong wind in this case from the south," he said.

Renfro said the Thursday system spun, bringing the real winds "that will crash like a big wave coming over the mountains." The Smokies, unlike most of the Appalachia range, run mostly east and west.

This past Thursday the wind gauges located at eight sites in the Smokies, including one on Cove Mountain, started picking up elevated winds at about 9 a.m. They came at a steady 50-plus mph with gusts to 97 mph until about 1 p.m.

He said a lighter system went through the previous Monday but didn't cause any damage. He added that on Thursday lighter winds came from the north later in the day as the spinning continued.

Pritchett said the events have been happening four or five times a year for a long time, but people are just noticing them more now.

“One reason is that we now understand what we are looking for and spot it more. That is why we have this high wind warnings and advisories. There are also a lot more people in the park so when these events happen a lot more people notice.”

Renfro said winds in the mountains have been measured for only about 20 years, not a long enough amount of time to tell whether these episodes are increasing in number, growing in intensity or simply being noticed more.

He advised to keep and eye on wind advisories and to watch what each designation means.

Code Red

Perrin Anderson of the Sevier County Mayor's Office said a Code Red alert went out at noon on Thursday that said: "Sevier County is under a high wind warning until 9 p.m. A shelter has been opened at the Pigeon Forge Community Center. Please be aware of downed power lines and tress and use extreme caution."

He said that at 1:07 p.m. a message was sent out to warn residents within a five mile radius of the burn area of a fire off Branam Hollow Road and to inform them of efforts to control it.

There was criticism of failing to alert people during the Nov. 28 firestorm.

Anderson added that a damage estimate for the wind event is still being put together.