Winds shape snow into rollers
SALEM – A South Dakota resident well-versed in sub-zero temperatures and snow saw something here that he had not seen up north – a weather phenomenon known as a snow roller.
Picture a roll of toilet paper sitting upon the snow, only in this case, it’s actually made of snow and just forms on its own, with a little help from a big wind.
Bryan Tierney and his wife Becky and their family are visiting family in the Salem area and spotted the snow rollers outside a few miles south of Salem Monday afternoon. He snapped some photographs and shared them so others could see the rare chunks of snow with the little holes in the middle.
The snow rollers measured 6 to 8 inches in diameter.
According to the National Weather Service Forecast Office website at www.erh.noaa.gov, “snow rollers are a rare meteorological phenomenon, in which strong winds blow chunks of snow or ice along the ground, causing them to accumulate snowpack as they roll (much like building a snowman).”
The website said several criteria must be met for snow rollers to occur: the ground must be covered by ice or crusty snow so fresh snow won’t stick; there must be about an inch or more of loose, wet snow on top of the icy surface; and strong winds are needed to roll chunks of snow along the ground.
“Snow rollers range in size from a couple of inches in diameter, to as big as a 30-gallon drum. Many times snow rollers may be hollow in the middle, since the snow in the center is loose and gets blown out of the roll,” the website said.
Tierney resides in South Shore, S.D., about 50 miles west of the Minnesota border and 110 miles north of Sioux Falls, the largest city in the state. Today in South Dakota he said the temperature was 15 below zero and 35 below zero with the wind chill.
“We’re more used to the wind chill,” he said.
“This actually isn’t too bad for us. We were surprised to hear Salem and all the schools had cancelled,” Tierney said, explaining that for them to cancel school where he lives, “The visibility has to be really down.”
All local schools and even area colleges shut down for today due to the chilly temps.
City Service/Safety Director Ken Kenst said the city received about 40 tons of salt on Friday, but the street department remains in conservation mode because that’s not enough to salt everything. With the low temperatures, he said the salt doesn’t work well anyway.
Residents still need to be careful, he said. There’s no parking ban in effect, but he said over the weekend when a lot of the snow fell, people had voluntarily moved their vehicles off the street anyway, which helped out the street department for snow removal.