Understanding what a snow roller is clears up a mystery to many residents of the plains and central states in America. Walking down a lane or through a snow covered field or meadow on cold winter days many people have observed a small “pile” of snow sitting alone in a central spot.
The passer by wonders fleetingly about the origins of the pile of snow but then forgets about it as they continue on their walk. Sometimes there will be several mysterious piles of snow in a field. But rarely will there be any trace of how the snow was deposited.
But now thanks to media coverage and the internet we can answer the question “What is a Snow Roller?” with an answer that sheds light on the mysterious piles of snow appearing in the frozen fields across the country. A small number of sightings and photos are available on the web.
On March 31, 2009 Tim Tevebaugh observed what looked like snow donuts scattered across the plains of south Idaho. He took pictures of hundreds of cylinder shaped rolls of snow with soft centers looking like holes. These snow rollers were about 18 inches high and the result of a very rare weather phenomenon; an event that provides a special combination of snow, wind, temperature and moisture.
The Sci-Tech Dictionary defines a snow roller as : A mass of snow, shaped somewhat like a lady’s muff, rather common in mountainous or hilly regions; it occurs when snow, moist as to be cohesive, is picked up by wind blowing down a slope and rolled onward and downward until it becomes too large or the ground levels too much for the wind to propel it further; snow rollers vary in size from very small cylinders to as large as 4 feet (1.2 meters) long and 7 feet (2.1 meter) in circumference.
The weather has to cooperate with certain conditions before a snow roller can occur. These are:
The ground must be frozen with a thin coating of ice or hard snow crust.
The frozen surface must be covered with a wet, soft covering of snow.
The wind must be steady and strong enough to move the snow rollers without blowing them apart.
Gravity can play a part in moving these rare formations down slopes in mountains and hilly locations.
Very few people have actually seen a snow roller because of the precise weather conditions needed for them to form. But many of us have seen the remains of a snow roller lying in a pile out in those snow covered fields.