Snow rollers dot a field along River Road in Duxbury in mid-January. Photo by Gordon Miller.

On the morning of January 17, Duxbury resident Donna Constant awoke to a peppering of large natural snowballs scattered across a neighboring field.

“My first thought was that they looked like pills on a white sweater,” Constant said.

This photo published in Vermont Life magazine in 1963 shows snow rollers on the Constant farm on Laurel Road in Waterbury with Camel’s Hump in the distance. Photo courtesy Donna Constant.

She posted a picture of these “snow rollers” on the “You know you grew up in the Waterbury area because…” Facebook page, which struck a nostalgic chord in the community.

The picture elicited excited responses from many members, some commenting that they remembered seeing snow rollers on the bus ride to Harwood Union High School in the early 70s.

“I was glad I posted it because it brought a lot of cool conversation and brought memories back. It really connected everybody,” Constant said.

That weekend was the first time Constant had witnessed the phenomenon for herself, despite living in Duxbury for almost 50 years. She was previously acquainted with snow rollers through a picture taken of her husband’s farm in 1963 for Vermont Life magazine, in which snowballs as big as tractor wheels dotted the field.

What exactly are snow rollers? Imagine a round hay bale or maybe a giant cinnamon roll – made out of snow, of course.

Snow rollers are a relatively rare phenomenon, formed only through a unique combination of atmospheric conditions. And they’re not unique to Vermont or even New England. “They are seen around the world. In any cold climate where there is snow and open fields, there are snow rollers,” said Mark Breen, senior meteorologist at the Fairbanks Museum in St. Johnsbury and weather forecaster for the popular Vermont Public Radio “Eye on the Sky” feature.

Breen says there are two key conditions necessary for the formation of snow rollers: First, a light dusting of wet and sticky snow must cover an older layer of dry, powdery snowfall.

“In other words,” Breen said, “It must fall on a very different texture so that the wet snow doesn’t stick to it.”

The other crucial element to get the ball rolling, so to speak, is the perfect amount of wind. “Wind speeds around 25 to 30 mph seem to be just the right speed, nothing stronger and nothing weaker,” Breen explained.

The snowballs collect powder until they lose momentum, typically ranging in size from 6-18 inches in diameter, he said.

Get a good look because these snow rollers have disappeared back into the landscape until the conditions once again are perfect for their formation. Photo by Gordon Miller.

The terrain that lends itself best to the formation of snow rollers is sprawling fields with a slight slope. And it was in just such an open range that local residents have observed this uncommon phenomenon once in a blue moon.

That recent weekend snowfall managed to accommodate the very particular circumstances that snow rollers require. The next day, another light coating of snow had fallen overnight, blanketing the rollers to provide some camouflage. The lumps remained scattered around the field when photographer Gordon Miller ventured out to capture some tricky white-on-white images before they disappeared.

Meanwhile, Constant’s Facebook post has provided an outlet for the community to celebrate this bizarre weather phenomenon and share some childhood memories, with no guarantee of when the elusive snow rollers might return.