LANSING, Mich. (WILX) - Have you ever seen anything like this? Viewer Ken Temple shared this video with WILX in Lansing. It was filmed at the Sleeping Bear Dunes.
"We watched two small clouds form over the Manitu islands then formed into one cloud," says Temple.
They watched as the Roll Cloud headed south toward them, passing directly over them.
To completely understand how roll clouds develop, it's important to understand some things about shelf clouds.
Shelf clouds are usually seen at the front edge of a thunderstorm, or line of thunderstorms- note that shelf clouds are not tornadoes or wall clouds.
A shelf cloud is the boundary between a downdraft and updraft, and when the shelf cloud passes you might feel an abrupt shift in wind direction and increasing wind speed- this will usually be followed with heavy rain or hail.
Unlike a shelf cloud, a roll cloud isn't attached to a storm. The storm might have fizzled, leaving the roll cloud alone- or the gust front surged well away from the thunderstorms. Occasionally, advancing cold fronts have been the cause of roll clouds.