Rare roll cloud ‘rolls’ through Rochester amidst strong Wednesday storms

Weather Blog

ROCHESTER, N.Y. — Gusty downpours and a few stronger thunderstorms pushed through the Western New York region early this afternoon.

One of them, in particular, formed a very unique type of cloud …

We call these clouds “roll clouds,” and they are a lot more scary to the eye than in actuality.

This tube shaped cloud is also known as an arcus cloud, meaning a low-level horizontal cloud that forms out ahead of the gust front of a thunderstorm. They are not connected to the ground and are NOT associated with tornadoes.

Photo courtesy of Katiria V. Negron

They’re caused by the forcing of cool, stable air from the downdraft of an advancing thunderstorm over warm, moist air out ahead of it, and in just the right environment, the converging of winds and sinking air can produce a “rolling” motion where the air condenses to form a roll cloud!

This likely occurred as a lake breeze boundary pushing south across Monroe county moved lots of lake cooled, stable air to help create the sinking motion as it met the rising, moist and unstable air from the south.

When this happens uniformly along an extended front, a roll cloud just like this one can form. In just the right situation you can get these types of air masses to form some very fun and interesting cloud features, and usually, it means the storm is weakening as it makes its way through an area.

Roll Cloud Time Lapse

Have any more fun cloud photos from today’s storms? Send them our way or tag us on social media!

Twitter and Facebook: @WxChristineG

Email: cgregory@wroctv.com

~Meteorologist Christine Gregory

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