'Mini tornado' forms in Kelowna as Arctic air hits Okanagan Lake

Residents of Kelowna, B.C., were treated to the sight of what looked like a mini tornado over Okanagan Lake Friday morning.

Environment Canada says the phenomenon was most likely a steam devil, caused by a blast of frigid Arctic air dipping below –20 C forming over the relatively warmer water below.

Kayla Pickles and her daughter Lizzie watched it advance slowly across the water over the course of about 20 minutes around 10:30 a.m.

"We thought it was a mini tornado," Pickles, who has lived in the city for seven years, said. "I've never seen anything like it."

Ellie Thornhill, who filmed a short video of the steam devil, said she watched it move south until it slowly disappeared.

"The only thing I could think of was a tornado," she said. "It was huge."

Environment Canada meteorologist Alyssa Carbonneau said after a warm December, the sudden blast of Arctic air that has settled over the B.C. Interior has "really made the conditions ripe" for interesting weather occurrences.

In the case of Kelowna, she said, the relatively warmer water of Okanagan Lake coming into contact with the –23 C temperatures above helped form the steam devil.

"You start to get steam fog, sometimes called steam smoke, forming on the lake," she said.

"As we get pressure gradient differences it can start to rotate and elongate into that column of rotating air."

Carbonneau said steam devils are similar to water spouts but tend to be weaker and don't extend as high into the atmosphere.

While they don't pose risk of damage, people are still advised to stay away from them if they happen to be on the water at the same time, she said. 

"It is similar to dust devils which we see over dry land rather than a tornado which is caused by a severe thunderstorm, and those tend to be associated with much stronger winds."

Still, she said, it was a reminder of "just how cold it is out there."