ST. GEORGE — A unique tornado briefly moved across empty desert landscape just east of Tonaquint Intermediate School late Thursday afternoon.
The phenomenon was captured on video by a St. George News reader but wasn’t confirmed as a tornado until midday Friday by the National Weather Service.
In the video, which can be viewed at the beginning of this article, a cloudy and dusty funnel can be seen rising from the hilly desert floor in an area above and between the school and the Shepherd of the Hills United Methodist Church.
Darren Van Cleave, meteorologist in charge at the National Weather Service’s Salt Lake City office, told St. George News the weather vortex was classified as a landspout, which he said is a type of tornado. However, landspouts fall somewhere between the dust devils typically seen in Southern Utah and more traditional tornados.
“From a meteorologist’s perspective, they would differentiate this from a tornado,” Van Cleave said. “The telltale sign is the rotation at the surface”
Reader Edwin Tony Borja provided to St. George News video of the landspout. He said he spotted it around 4 p.m. in the Tonaquint area of St. George. The video angle is toward Dixie Drive near the corner of Tonaquint Drive and W. Curly Hollow Drive.
Landspouts weren’t defined until 1985 when it was categorized by research meteorologist Howard Bruce Bluestein, who invented the TOTO device that inspired the fictional Dorothy device in the movie “Twister.” The exact mechanism is involved in the formation of waterspouts, which are seen off coastal beaches and other water bodies.
Van Cleave said in the Enhanced Fujita (EF) scale, the Tonaquint landspout tornado would be classified as an EF-0 – the weakest category of tornado. EF-0 tornadoes are 40-72 mph, according to the National Weather Service, and capable of “some damage to chimneys; branches broken off trees, shallow-rooted trees uprooted, sign boards damaged.”
And Van Cleave said while landspouts rarely are harmful, they can cause damage. If it had traveled southwest, staff and students at Tonaquint Intermediate on Curly Hollow Drive might have had to spend their Friday cleaning up.
“Usually, a landspout is more of a curiosity than a dangerous issue, but if it had gone through a neighborhood, there could have been wind damage,” Van Cleave said.
While far from the scale, the Tonaquint tornado came 23 years to the day of an EF-2 (113-157 mph) tornado that killed one and injured more than 100 in the Salt Lake City area in 1999.
Other vortex-like phenomena in Southern Utah include a funnel cloud seen in Cedar City in 2019 and a Panguitch tornado in 2016.
The landspout touched down around the time a heavy rain hit about three miles north along Sunset Boulevard and in Ivins and Santa Clara
The landspout was different than dust devils, which the NWS describes as vortices created from strong surface heating when there is cooler air above, usually at the interface between different surface types, such as asphalt and dirt. The less-dense heated air causes instability with the denser, cooler air above.
Landspouts share the same difference between warmer air on the ground and cooler air above as dust devils. What differentiates them from dust devils is that ground circulation is drawn into clouds above, creating stronger winds and possibly a rotation in the clouds above. Before dissipating, the Tonaquint vortex can be seen getting to the cloud bottom.
Landspouts sometimes can’t be seen at all, appearing as nothing more than swirling debris on the surface unless dust and condensation are kicked up.
There are two major differences between dust devils and tornados. For one, dust devils are not usually as high in wind speed and only on rare occasions are destructive. Also, by their nature, tornados can only form in cloud cover while dust devils can be seen on clear, cloudless days – as Southern Utahns who have seen dust devils can attest to.
This week’s unstable weather conditions have created other unique weather phenomena locally.
Moonbows over Cedar City
Reader Shari Shumway submitted to St. George News an image of a moonbow.
The arc can be seen going across the sky, west of Cedar City. Shumway said it occurred at 12:40 a.m. Wednesday.
While rarer, moonbows actually are caused by the same mechanism that causes rainbows, the weather service says. Unlike rainbows, which are created when light from the sun reflects off large droplets of water in the lower atmosphere, moonbows happen when light reflected from the moon hits the same droplets and the color bands of light split off like a prism.
The sun doesn’t lose all the credit. The light from the moon is actually light from the sun reflected off its surface.
Besides the monsoonal moisture in the air, it may have also helped matters that it was a slightly brighter moon this week with the last “supermoon” of 2022 on Thursday. According to NASA, a supermoon occurs when the moon reaches the perigee, or closest point of its orbit, to the Earth at the same time it is in its full moon phase.
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