Friday, July 30, 2021

international

Oklahoma glider pilot flies around landspout tornado


Oklahoma City native David Evans has been a pilot for about 30 years, but few things compare with what he encountered while flying his glider Sunday. Evans came face to face with a bona fide tornado - and decided to hitch a ride on the upward-moving air around it.

Weather wasn't conducive for strong thunderstorm activity or tornadoes in the Sooner State on Sunday, but Evans found a landspout, or a borderline tornado that forms in a way similar to many waterspouts or dust devils. That meant it wasn't born from a thunderstorm or cloud-based rotation, but rather developed from the ground up.

It also couldn't be spotted on radar, and there were no obvious large-scale weather features that would have clued meteorologists into the chance for tornadoes.

"Realistically, it was more of a landspout, but we sort of have no justification as to why it occurred," said Ryan Bunker, a meteorologist at the National Weather Service in Norman, Okla. "We didn't have any answers."

Instead, it appears a small, broad surface-based whirl cooked up in the heat of the afternoon sun - as is routine during the summertime.

"I have a little motorglider, and you look for these thermals to stay aloft," said Evans, who hadn't been optimistic about the day's gliding prospects. He took off from Wiley Post Airport on the northwest side of Oklahoma City anyway, hoping to get lucky.

"I motored around Tuttle and Minco, and then I saw some hawks," recalled Evans. "They're always a telltale sign of where a thermal might be. I started getting an indication I was getting lift, so I circled in there with them."

What was a broad, weak, invisible circulation that Evans was riding quickly became drawn into a cloud developing overhead. That stretched it up to the cloud base, causing it to become more narrow and strengthen. Before long, a funnel cloud appeared.

"[The thermal] was raising me up at about 100 or 200 feet per minute," said Evans. "Then all of a sudden that vapor funnel started forming. It was going down and down and down, but there was no turbulence. I just kept flying around that thing."

It was unclear to Evans at the time, but apparently the funnel did have a ground circulation attached to it - making it bona fide tornado, albeit a weak one. Winds were probably less than 75 mph, but it did stir up vegetation and hay on the property of Judy Curry.

That would make it an official tornado, similar in formative processes to the picturesque funnel that danced east of Denver last week.

"It was really pretty," said Evans. "It went from base of clouds . . . it was a rat's tail-looking thing."

Back at the Weather Service, Bunker was equally impressed.

"I've seen cool drone footage, but you never see someone in their own plane flying right next to a funnel," he said.

Bunker's hypothesis is that there was a residual weak boundary of some sort draped across the area, sufficient to enhance low-level spin. That might have helped a tiny whirlwind form while also initiating upward-growing clouds above.

"You can stretch it and get a brief spinup," said Bunker.

In the meantime, Evans says he's looking forward to taking to the air again soon - but doubts he'll see anything so spectacular again.

"I've never seen anything like that," he said.

Published : June 15, 2021

By : The Washington Post · Matthew Cappucci