I was driving through Clovis, New Mexico, nervously watching a black cloud with a shelf formation to the south and waiting for a call from a family member who was checking the weather on the internet.
Suddenly, before me, I could see a funnel cloud forming in the middle of the intersection. I didn't have time to stop or turn around. I drove right past it, perhaps even through it, my hands sweating and shaking. The truck moved slightly to the right as debris pelted the doors and windows.
Convinced that I had driven through a tornado in its early stage of formation, I continued onto the next block and stopped the truck, then quickly looked around for shelter or a ditch. I opened the door of my truck and stepped outside, facing the intersection, prepared to run. A line of cars and trucks had parked on both sides of the road. People were running for nearby buildings.
I looked back at the intersection, watching as I ran alongside my truck. The funnel cloud looked like a fat dust devil, sucking in debris from the pavement and the street gutters nearby, twisting rather slowly, loosely, as if it wasn't holding together very well. Then, as quickly as it had formed, it disappeared.
I stopped and stared. It wasn't sucked back up into a cloud. In fact, the shelf cloud still appeared to be on the outer edges of town. One second, the swirling debris was in the intersection, the next second, the debris was falling to the ground. Why? Because it was not a tornado in the intersection, it was a gustnado!
Dust Devils in Thunderstorms
Gustnadoes are most common in the American Midwest and the term is not commonly used by meteorologists. According to the National Oceanic and Atmospheric Administration (NOAA), gustnado is actually a slang term describing a "short-lived, ground-based, shallow vortex." It is a dust devil that develops on the gust front of a thunderstorm, generally near a thunderstorm that has a shelf cloud on the front, or forward-moving side.
However, gustnadoes can also form in the rear-flank downdraft of a thunderstorm where there are weather conditions that are favorable for the formation of tornadoes. Due to the weather conditions in these positions it is possible for the gustnado to suddenly become part of a tornado that is forming at the same time.
Anatomy of a Gustnado
Like tornadoes, gustnadoes vary in height and strength. They can be 30 feet tall, or 300 feet tall, but there is no obvious visual connection to any clouds. There may be rain at the time they form, but this might make it less visible. They are best seen if they form before the rain starts to fall. Without rain to obscure the view, the gustnado looks like wispy, swirling clouds, or a dust devil.
As for speed, a gustnado can move 60 to 80 mph, which is the equivalent speed of an EF0 or EF1 tornado, though it is not, by any means, considered a tornado. The EF stands for Enhanced Fujita Scale, a scale used for comparison, introduced in 2007 to more accurately reflect tornado damage. (The Fujita Scale is named after revolutionary storm researcher Ted Fujita, who designed the original scale in 1971, and also discovered downbursts and microbursts.)
Indiana State Fair Stage Collapse, August 13, 2011
At 6 p.m. on August 13, 2011, the NOAA office in Norman, Oklahoma issued a Severe Thunderstorm Watch for a storm in Central Illinois that appeared to be moving into Indiana. At that time, the Indiana State Fair in nearby Indianapolis was in full swing. According to an article in Scientific American, radar images show the thunderstorm collapsing at 8:35 p.m. This action sent a gust front three miles ahead of the storm's location.
At 8:45 p.m., the Indiana State Police warned people in the area of the grandstand, which was between performances, of the coming storm. At 8:48 p.m., winds from the gust front, traveling at 53 mph, hit the Indiana State Fairgrounds and the grandstand collapsed, killing four people at the scene. Forty people were injured by the grandstand collapse and hundreds of others from flying debris. Three more people died later from their injuries.
According to radar images and videos taken at the scene that were examined by Accuweather Senior Meteorologist Henry Margusity, a possible gustnado traveled from left to right across the stage. Margusity explained his theory in Scientific American. This particular gustnado was both violent and deadly due to its location in a highly-populated area.
Powerful Kansas Gustnado
The gustnado that destroyed the grandstand at the Indiana State Fairgrounds was relatively short-lived, unlike the gustnado that ripped through Williamstown, Kansas earlier in the year.
On Sunday, April 3, 2011, northeast Kansas registered record high temperatures, an almost sure sign that a spring storm will follow in the afternoon. By Sunday evening, several northeast Kansas towns were reporting hailstorms, and straight-line winds with speeds of 70 to 80 mph tore through the countryside. As the storms continued to move through Kansas, they seemed to grow in strength.
Suddenly, a solid, firm, and powerful gustnado formed near Williamstown, Kansas on Highway 24. The storm lasted longer than most gustnadoes, which seem to fall apart in less than a minute.
Damage surveys following the storm reported two center pivot irrigations were flipped, an outdoor shed was torn to pieces and numerous trees lost branches that once stretched across the gustnado's path.
According to weather reports, the Williamstown, Kansas gustnado was "strong and persistent," yet another reminder of the power, and unpredictability, of nature.
Sources
- Buchman, Heather. "Gustnado May Have Caused Indiana Stage Collapse." Scientific American. Posted August 15, 2011. Retrieved October 23, 2011.
- Buckley, Bruce. Hopkins, Edward J. Whitaker, Richard. "Whirlwinds and Dust Devils." Weather: A Visual Guide. Firefly Books, Ltd. Australia: 2004.
- "Gustnado Definition." National Weather Service Weather Forecast Office. Morristown, Tennessee. National Oceanic and Atmospheric Administration. Retrieved October 24, 2011.
- "Severe Weather: Sunday, April 3, 2011." National Weather Service Weather Forecast Office. National Oceanic and Atmospheric Administration. (NOAA) Topeka, Kansas. National Oceanic and Atmospheric Administration. Retrieved October 24, 2011.
Darla Sue Dollman - Darla Sue Dollman, BA, MFA, has expertise in classic films, the Old West, boating, and animals.
