According to the National Weather Service under National Oceanic and Atmospheric Administration in the United States, snow rollers are typically cylindrical in shape, hollow in the center with multiple layers forming its outer cover – somewhat like a cinnamon roll. It is formed when strong wind gusts blow the snow and it picks up everything on its way.
Though the phenomenon is rare, such snow rollers were spotted in Fairfield, Idaho, earlier this month. The last time they were seen in Idaho was in 2009 in Lewiston.
Check out the possible conditions for the forming of snow rollers, according to meteorological website weather.com.
-Existing snow cover, so additional snow will not always stick to it
-Wet, loose snow on top of the icy snow cover
-Wind strong enough to propel snow roller forward
-The slope to the ground.
(Photos from weather.com)