By Jim Knippenberg
The Cincinnati Enquirer

An 8- to 10-inch snow roller on the grounds of Woodward High School in Bond Hill (Glenn Hartong photo) | ZOOM |

Something most people have never seen rolled into town Wednesday morning: Snow rollers. All over the place but mostly in open spaces.

Snow rollers, according to Robin Gerhardt at the National Weather Service in Wilmington, are cylindrical masses of snow that range from the size of a fist to about 4 feet long. They resemble bales of hay.

It's the same principle as making a snowman, except it's nature doing the rolling. And it doesn't happen often, says Paul Pastelok, an AccuWeather meteorologist in State College, Pa.

A snow roller on the Eagle Tee driving range in West Chester Township. (Michael Snyder photo) | ZOOM |

The snow has to be fresh and moist enough to be cohesive but not as moist as the snow we had Monday. There has to be a wind strong enough to get the snow rolling (40 mph sustained, Pastelok says), but not so strong it blows it away. And there has to be a slope, at least initially, for momentum.

"Snow rollers are most common in mountainous regions, but southern Ohio is hilly enough," Gerhardt said. "No one in the office can remember it happening here."

"It's a very rare event," Pastelok says, "because so many conditions have to come together just so to make it happen."

E-mail jknippenberg@enquirer.com