Rare sighting: Naturally rolled snow 'hay bales'

Rare sighting
Naturally rolled snow 'hay bales'

Nope, this image above was not a result of the farmer's hard work, but rather the wind's!

Snow rollers have been recently spotted in southern Ontario, following heavy falls of snow here where over 100cm accumulated.

These cylindrical snowballs form when freshly fallen snow is blown by strong winds down a hill. They are quite rare to spot however, given the specific set of conditions needed to form.

This includes:

Recent and sufficient snow depth that is light enough to roll, but moist enough to stick together

Temperatures just a few degrees above freezing, around 3-5C so some small surface melting can allow the snow to stick

Moderate to strong winds to roll the snow, ideally with a wind speed of around 30mph

They have been known to occur in our neck of the woods before too, and as we head towards winter it's certainly something we will keep our eye out for! Have you ever seen this rare winter phenomenon?

Weather & Radar editorial team

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