Rare weather phenomenon occurs near Lake Diefenbaker

By Jay D Haughton

Have you ever heard of or seen snow rollers?

Well, those in Macrorie have, as hundreds of snow rollers covered Lake Diefenbaker near the community last Friday.

Snow rollers are a rare meteorological phenomenon in which snowballs are formed naturally by being blown down a hill or along the ground, picking up snow along the way.

Environment and Climate Change Canada meteorologist Terri Lang said it takes a perfect storm for snow rollers to appear, involving wind, temperature and moisture.

“Generally, what we need is fresh snow and (it) has to be really sticky so that it all binds together really well and has to have a really high moisture content to make it sticky,” Lang said.

“The other thing is really strong winds. When the winds start blowing on this sticky snow and if it can catch the snow, it will allow it to start rolling. The winds have to be strong and sustained and once the rolling gets going, it can push them fairly long distances.”

Once they’re formed, Lang adds they will look similar to cinnamon buns. In addition, if there is one, there are probably several, as they are created in bunches.

To make this event even rarer, Lang looked back at the weather conditions for Jan. 6, and they weren’t favourable for creating snow rollers.

“Something must have happened down there,” Lang said. “The winds probably were funnelled down the lake and they got a pocket of warm air. There hadn’t been any fresh snow, but there was that rime-icing which could’ve made it sticky enough to get going.”

She hasn’t seen a snow roller since January 2021, which was only the fourth time she has seen one in her career.

“They happen every few years or so,” Lang said. “We had a big storm through Saskatchewan and it was classic conditions that we got. It helps in an open field and you can really get the wind going. We saw the wind speeds get up to 60 or 70 kilometres per hour.”

Other names for snow rollers are snow bales, snow donuts, and wind snowballs.