These jelly roll clouds, called morning glories, are so rare that the only reliable place to find them is at the Gulf of Carpentaria during Australia’s spring, August to November. They form there because of Cape York Peninsula’s shape and orientation to the wind.
In photographs from above these clouds look peaceful. From the ground they are awe-inspiring, rolling across the landscape on their horizontal axis as shown in this video from Leelanau State Park, Michigan in 2016.
Morning glory clouds are extremely rare in the U.S. but I have an idea why one formed at Grand Traverse Bay. Notice the shape and orientation of the Leelanau Peninsula. It’s like Cape York on a smaller scale.
Read more about morning glories and why glider pilots love them in this vintage article: Morning Glory.
(photo and Gulf of Carpentaria map from Wikimedia Commons, video by Chad Bousamra on YouTube, Michigan map screenshot from Google Maps; click on the captions to see the originals)