There was a lot of wet weather and strong winds across Wyoming on Saturday, and they combined to produce a short-lived but threatening landspout tornado in Sublette County.
Big Piney resident Stephen Nelson was out on his deck when he noticed something swirling around north of town.
“I was doing something and thought, ‘That’s a dust devil.’ Then it was a big dust devil. Then it was a funnel cloud," Nelson told Cowboy State Daily.
The funnel cloud snaked its way from the ground up to the ominous storm clouds overhead. Nelson spotted it around 11:55 a.m., and it was gone by noon.
“The storm has moved over towards the Pinedale area,” he said. “I’ve heard, second and third hand, that they’ve lost power in Pinedale.”
According to the website PowerOutage.com, over 732 Rocky Mountain Power customers reported power outages in Sublette County around 1:30 p.m. The issue had been addressed by 2 p.m.
However, landspout tornadoes weren’t the primary concern of Wyoming’s meteorologists on Saturday. They were keeping a closer eye on potential 70-mph wind gusts and whether this weather would bring any precipitation.
“We’re busy today,” said meteorologist Taylor Wittman with the National Weather Service (NWS) office in Riverton. “We’ve got some active weather, but the tornado was a bit of an anomaly. Our major concern is 50 to 70 mph wind gusts across Wyoming Saturday."
It’s A Twister?
Cowboy State Daily meteorologist Don Day said the funnel cloud spotted near Big Piney was “a well-formed landspout.” It’s like, but not exactly, a tornado.
“A landspout is defined as a tornado that does not arise from organized storm-scale rotation,” he said. “You get a circulation near the ground that is brought into an updraft, that then causes that funnel situation.”
Even though they tend not to be long-lived, landspouts should be taken seriously. Day said they have a destructive potential comparable to that of a regular tornado.
“You can get 70, 80, 90 mph wind gusts in a landspout,” he said. “They're not going to bring the intensity of the wind and the destructive power of a tornado, but they can certainly cause damage.”
Landspouts tend to be more common in the spring and summer, especially when Wyoming’s area gets humid. When summer thunderstorms carry moisture into Wyoming, the likelihood of landspouts increases, as was seen in Sublette County on Saturday.
As the system moves, there’s a chance more landspouts could form. Day believes it’s a risk worth taking seriously.
“We should be on our guard for more of these, especially in northern and far-eastern Wyoming, for the next 36 hours,” he said.
Watches And Warnings
The NWS issued a Severe Thunderstorm Warning for Riverton and Lander on Saturday afternoon, anticipating penny-sized hail and wind gusts as high as 60 mph.
Meanwhile, 15 counties in central and eastern Wyoming were under a Severe Thunderstorm Watch until 9 p.m. Saturday. The NWS was monitoring “a cluster of strong thunderstorms” with gusty winds and hail.
By 2 p.m., there were thunderstorm storm clouds over northwest Wyoming, too.
Wittman said the sudden surge of severe weather is primarily due to an abundance of moisture, which is what most of Wyoming needs.
“We actually have some okay moisture in the area today, by Wyoming standards,” he said. “The system moving in is bringing enough moisture to make clouds and produce storms. The physics in the air is enough for some of the stronger storms we’re watching.”
Some spots in Wyoming, like Johnson County and the Bighorn Basin, might get 0.1 inches of precipitation from this system. It's not a lot, but every drop is welcome.
Severe summer thunderstorms often come with a higher risk of strong winds and hail, which is exactly what Wittman and his colleagues were watching on Saturday.
“The main hazard will be Saturday afternoon and evening,” he said. “We’ve already seen some 60-mph gusts, but the primary threat will be along western Fremont County, and the Wind River Range, down to Rock Springs and the South Pass area, and that will move eastwards toward Casper.”
Wittman emphasized that this was a dynamic system that was being closely monitored. The timing and severity of its impacts can change quickly, so everyone in the affected area needs to be on their toes.
“These storms can intensify as the day continues,” he said.
Sunnier Sunday
All the watches and warnings issued by the NWS end before midnight, but that doesn’t mean it’ll be sunny and dry on Sunday. Wittman said the Saturday system might continue impacting Sunday’s weather.
“Saturday should be the bigger day for thunderstorms, hail, and wind, but we do have the chance of showers lingering overnight, and storms again on Sunday,” he said.
However, Wittman doesn’t anticipate an ongoing threat of landspouts. The Sublette County landspout was an oddity during a day of active summer weather in Wyoming.
“That landspout was probably the result of a storm initiation,” he said. “That’s how you might get a little spin-up, but the bigger risk is strong winds, not landspouts.”
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
