Most of the Desert Southwest averages less than 10 inches of precipitation a year, but when it rains, it pours. Parts of Arizona, Nevada and Utah got a bit more than they bargained for Sunday when afternoon monsoonal downpours popped up, with several tornadoes touching down.
Tornadoes are a rarity in the southwestern United States, but multiple twisters were on the ground simultaneously for a time Sunday evening. One churned ominously close to Interstate 15 in Nevada, and another was photographed from near Lake George, Utah, as it slipped into northern Arizona.
Part of southern Arizona was included in a Level 1 out of 5 marginal risk for severe thunderstorms by the Storm Prediction Center in early morning forecasts. The chance of tornadoes was never advertised.
“[I was] looking south and that’s when I first saw the funnel,” wrote Brody Cowing, a rising junior in high school who was visiting his grandparents near St. George, Utah, at the time. Cowing plans to attend college and study atmospheric sciences or meteorology, and had known severe thunderstorms were possible.
“I brought out my new camera onto the back porch of my grandma’s house just to try to catch some photos of the mammatus on the anvil from the [western] storm near Mesquite,” he wrote. Mammatus clouds, which form on the underside of thunderstorm anvils, resemble bubble wrap-like pouches. “I tried bagging some cool pics, but didn’t have much luck [at first].”
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Then things changed. As soon as he looked south, he noticed a pendant funnel cloud attached to the underside of a distant storm drifting south into the Grand Canyon-Parashant National Monument area. A second funnel was visible to the right, or west, of the first. Before long, the first funnel had snaked all the way to the ground, writhing in a precarious yet menacing serpentine dance.
“It manifested from there, becoming more defined as the second one tried to develop,” Cowing wrote in a direct message on Twitter. “They both lasted several minutes (the first tornado & the 2nd funnel).”
At the same time, the National Weather Service in Las Vegas was maintaining a tornado warning for a separate rotating thunderstorm near Mesquite, Ariz. At one point, the Weather Service noted that the public confirmed a tornado, and it included a stretch of Interstate 15 in the warning.
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If that winds up having been the case, then two twisters will have been on the ground simultaneously.
“We did not verify that one [yet],” said Dan Berc, the warning coordination meteorologist at the Weather Service office in Las Vegas. “We issued based on a public report. We saw there was rotation on the radar.”
There was a report of a funnel cloud, but it’s unclear whether it touched down.
Tornadoes in Arizona and Nevada are rare. Arizona averages only five a year across the entire state, and Nevada nets a mean of two. Given the aridity of the Southwest, cloud bases are ordinarily too high to allow tornadoes to touch down. Mid-level winds are also generally too weak to foster rotation within thunderstorms.
@abc4utah check out these tornadoes my wife and myself shot 30 miles south of Santa Clara, Ut at 5:30pm. 3 confirmed funnels, 2 of which touched down. One was trying to become an elephant out sideways. One rope. And a classic stovepipe. Incredible evening! pic.twitter.com/aZXleeKjSY
— Jake Hough (@notaMaterialist) August 22, 2022“When we get tornadoes, it’s not the typical pattern you see in the Midwest,” Berc explained. “We get most of our thunderstorms during the monsoon season, which we’re in the thick of right now. When we get them, they’re generally smaller and non-supercellular.”
In this case, thunderstorms were surfing the backside of a narrow strip of low pressure, meaning they were riding in from the north. Cold air aloft also allowed for big hail in storms, but most of it, perhaps to near-golf-ball size, fell in sparsely populated areas.
“With this kind of environment we have, we’ll often get large volumes of small hail,” Berc said.
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