Rare weather event produces spontaneous snowballs in Idaho

BOISE, Idaho (AP) — Thousands of snowballs rolled in a flat central Idaho field look like the work of hundreds of ambitious kids — except there are no human tracks.

A rare weather event caused the spontaneous snowballs at the Nature Conservancy's Silver Creek Preserve and surrounding fields near the tiny town of Picabo.

So-called snow rollers are so rare and fleeting that the precise weather conditions needed to form them are not defined, said Jay Breidenbach, a meteorologist with the National Weather Service.

In general, it takes an unusual combination of a couple of inches of snow with the right water density and temperatures near freezing, followed by strong winds, he said.