When I was growing up, back in the time when grade schoolers were allowed to play in the snow during recess, we would make “snow forts,” making several large snowballs maybe 3 feet wide. Today, our warmer winters and changes in policies have made this just a memory. While making snowballs is not as possible or acceptable as it used to be, sometimes nature will create something similar.
A couple of weeks ago I got a message from an Extension colleague in the west-central part of the state. They were asking about what appeared to be snowballs that had appeared in several people’s yards. Being the weather geek I am, I enthusiastically let them know that what they had were snow rollers!
Snow rollers are rare in Illinois. They are more common in Canada and points north. Weather conditions must be unique for snow rollers to occur. Snow must be fresh and moist, and there must be strong winds. The ground must also be clear of standing plants and residue. Temperatures near or slightly above freezing are ideal.
Snow rollers are not snowballs. As the name implies, they are shaped more like a tube. Strong winds will make some snow start to drag across the surface. Additional snow will collect on the moving snow, creating a small sheet. This sheet continues to roll, gaining more snow. Once the roller is too heavy for the wind to move, it stops. They often will have a hollow center. Fresh snow on top of older, crusty snow or ice also makes snow roller creation easier. Most snow rollers are only a few inches in diameter, although in very rare instances, they can get up to 2 feet!
If you ever have a chance to see snow rollers for yourself, take lots of pictures, because you may not see them again for a long time.
About the Blog
The All About Weather blog by Duane Friend explores the environment, climate, and weather topics for Illinois. Get in-depth information about things your weather app doesn't cover, from summer droughts to shifting weather patterns. Never miss a new post!