Rare weather event produces spontaneous snowballs This Jan. 30, 2016 photo provided by The Nature Conservancy shows a rare weather event that caused spontaneous snowballs at The Nature Conservancy’s Silver Creek Preserve and surrounding fields near the tiny town of Picabo, Idaho. (Sunny Healey/The Nature Conservancy via AP)
Rare weather event produces spontaneous snowballs
Lexile

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.
 
Preserve manager Sunny Healey spotted the cylindrical shapes up to 18 inches high on Jan. 30 following an overnight windstorm. They created long lines in the snow as they moved.
 
"You could see the tracks that they made, and I thought that was really curious," Healey said. "I had to stop a couple times. Then, along Highway 20, there were thousands of them."
 
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. Snow rollers up to 18 inches are especially rare.
 
"Those are some pretty big rollers," Breidenbach said. "I've seen some small rollers, but never that big."
 
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.
 
"It can't be real dry snow or it would blow into drifts," Breidenbach said.
 
Rollers require some type of firmer base, such as a frozen layer of earlier snow, for the new powder to start rolling on. Plus, the wind must be strong and steady but not with powerful gusts that could damage the formations.
 
"It would probably blow them apart because they are fragile," Breidenbach said.
 
It snowed on Jan. 29, with the snow becoming wetter toward evening, Healey said. She lives at the preserve and said winds woke her up.
 
In her five years working at the preserve, she had never seen such an event, but a local rancher in his 70s told her he's spotted them twice in previous decades.
 
"We know basically how they form and why they form, but we don't know the exact details," Breidenbach said. "It would be interesting to go there with some weather instruments to watch them form."

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CRITICAL THINKING QUESTION
How did wind create the snowballs?
Write your answers in the comments section below


COMMENTS (64)
  • tyn-2-bar
    2/26/2016 - 04:06 p.m.

    In order for rollers to form "Rollers require some type of firmer base, such as a frozen layer of earlier snow, for the new powder to start rolling on. Plus, the wind must be strong and steady but not with powerful gusts that could damage the formations." which is exactly what happened.

    I think that if a four-year-old saw this happening he/she would think invisible people are making snowballs.

  • landryb.-tay
    2/29/2016 - 09:26 a.m.

    The wind creates the snowballs by having a couple inches of snow, the right water density, and temperatures near freezing.

  • masons.-tay
    2/29/2016 - 09:30 a.m.

    Just like the story of the rocks moving in the dead sea that the wind blows and the water and snow roll together and-ta DA!-a snow roller!!!

  • endsleyn.-tay
    2/29/2016 - 11:21 a.m.

    I wish it would either snow or just stay warm where we live!!????

  • trinityt.-tay
    2/29/2016 - 11:24 a.m.

    Where does this usually happen?

  • leonac.-tay
    2/29/2016 - 11:27 a.m.

    The wind blew them causing them to roll And collect snow

  • landony.-tay
    2/29/2016 - 11:27 a.m.

    It pushed the snow and it began to roll into a snowball.

  • kyrak.-tay
    2/29/2016 - 11:45 a.m.

    Because the wind has to be strong enogh to roll it on the old snow.

  • blainej.-tay
    2/29/2016 - 03:37 p.m.

    The wind pushed them into that shape.

  • noahc.-tay
    2/29/2016 - 04:14 p.m.

    To didn't think those passage was very interesting but I guess I can see were people would like that.

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