High winds and snow in western Pennsylvania combined Monday to create hundreds of examples of natural sculptures known as snow rollers.
Many residents of the Oil City area woke to find found the curious formations in their yards, gardens and fields.
JoAnn Heckathorn told The Derrick of Oil City that "beautiful columns" the size of jumbo rolls of paper towels were everywhere in her yard.
According to the National Weather Service, a snow roller is a rare meteorological phenomenon in which large snowballs are formed naturally when chunks of snow are blown along the ground by wind.
The shapes are often hollow, and the conditions need to be precisely right for them to form, according to the weather service. For example, wind must be strong enough to move the snow rollers, but not so strong they're blown too fast.
Weather service records from various states note that snow rollers can be as small as a golf ball or as large as a 30 gallon drum, but typically average 10 to 12 inches in diameter.
The area where the phenomenon was spotted Monday is about 90 miles northeast of Pittsburgh. Some residents said the shapes resembled bowling balls, while Charles Keith of Franklin described "500 Tootsie Roll-like" forms in an empty field nearby.
Nancy Graham, 68, said her yard is covered with the rare forms, and that it's something she had never seen before.
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