Living along the West Michigan Lake Michigan shoreline I tend to watch the weather for changes. Something like a sailor, just with both feet firmly planted on the shoreline. When storms are in the forecast I keep an eye on radar throughout the day in the event something crops up. On Sunday evening July 26, 2020 that’s just what happened. Shelf clouds are fun to watch form on the horizon and they develop a menacing look as they approach and draw closer. My experience has been most of the shelf clouds I have captured on Pere Marquette beach in Muskegon Michigan will develop and move in from either the North or the West.
A ridge of menacing clouds starts to form on the horizon and as it approaches the air temperature changes. The cloud morphs from a grey line on the horizon to a “monster” white on the top and dark on the bottom as it “rolls” in. A shelf cloud is a low-hanging, well-defined, wedge-shaped formation that occurs along the leading edge of the gust ushering in a thunderstorm. Updrafts feed warm, moist air into the thunderstorm to provide it with the energy it needs to survive. The day this shelf cloud formed the beach was packed as daytime temperatures were near 90 with high dew points.
The downdraft consists of dense, rain-cooled air that sinks to the surface underneath a thunderstorm. The air from a downdraft pools up at the surface beneath the storm in what’s known as a cold pool and tilts the updraft letting the storm take shape and begin to move dramatically over the lake. As the outflow boundary or gust front begins to lead and pull the thunderstorm south it is ingesting warm, moist air and the results are dramatic. As the updraft’s warm, moist air rises up along the outflow boundary, it cools and condenses into a shelf cloud perfect for picture taking.