What are 'snow rollers'? Photos of rare phenomenon in Michigan spark curiosity

(NEXSTAR) – A photo of “snow rollers” that formed during a recent weather event in Michigan gained traction on Reddit earlier this month, sparking curiosity over the whimsical, snowy sighting.

“This is the coolest thing I've ever seen,” one viewer wrote, remarking on the dozens of doughnut-shaped snowballs peppered across a field.

The peculiar formations inspired nicknames including “snonuts,” “Snoghetti-Os” and, more crudely, “snowman toilet paper.”

But as otherworldly as they sometimes look, snow rollers are simply a natural phenomenon that can occur in snowy and windy conditions — or rather, very specific snowy or windy conditions.

As noted by the National Weather Service (NWS), snow rollers can form when a layer of “light but sticky snow” covers the ground. Strong winds — or, in some cases, gravity — then cause chunks or little sheets of this soft snow to roll over onto itself, creating a small tube that can continue to grow during subsequent winds.

They’re also more conducive to forming when the light, sticky snow is covering a layer of “older, crusty snow,” according to Duane Friend, a climate change specialist with the University of Illinois Extension.

“They can be found more often on hillslopes where gravity can start the rolling, but are still rare,” said Friend, who last saw snow rollers in-person about 20 years ago. “In flat areas … there has to be a fairly strong wind (about 25-30 miles per hour), to get them to form.”

Relatively unobstructed landscapes (no significant growths or vegetation) and near-freezing temperatures are also more friendly environments for snow-roller formation, Friend added.

Although rare, snow rollers have been spotted across other snowy parts of the globe from time to time, most commonly in open areas of the countryside. In North America, snow rollers have been observed from Colorado to Vermont, and even once in downtown Ottowa, Ontario, the CBC reported in 2018.

It’s very possible that most of us, however, will likely never see a snow roller — at least outside of a photo posted to the internet.

“So cool!” one viewer wrote under the pictures of snow rollers on Reddit. “I’ve lived in Michigan my whole [67-year-old] life and have never seen, or heard of rollers before.”