Snow rollers from Winter Storm Rocky on Feb. 26, 2013. (Photo credit: Lucinda Gates via NWS-Wichita)
Most kids growing up in colder climates have made a snowman. You start by rolling a lump of snow into a large enough snowball for the bottom segment of the snowman.
Did you know in certain conditions, the wind can take care of that itself?
What you see in the photos above are called snow rollers.
Snow rollers are most common in hilly or mountainous terrain. Basically, strong winds pick up moist snow and blow it along the ground, eventually building a cylinder of snow, which is often hollow in the middle. When the snow roller grows too large for the wind to propel it farther, it stops.
Here are the optimal conditions for snow roller generation, according to the National Weather Service:
- Existing icy or crusty snow cover, so additional snow will not stick to it.
- Additional wet, loose snow on top of the icy, crusty snow cover
- Wind strong enough to scoop out balls of snow and propel snow roller foward.
- At least some slope to the ground.
These snow rollers can be as large as barrels, as you can see in the photo above from Craigmont, Idaho. In a field, they can resemble spilled Cheerios on their side, or rolls of toilet paper.
Snow rollers can also leave tracks where they aggregated the wet, loose snowcover, similar to the famous sliding rocks on the "Racetrack" in Death Valley.
We'd love to see your photos or video of snow rollers! Share them with us at iWitnessWeather.
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From Gibson, La. in December 2008. iWitness Weather contributor jamiecg.