GRAND RAPIDS, Mich. (WOOD) — We have a few more days with sunshine and temperatures in the 80s this week before our weather pattern undergoes some big changes next week. Cooler air is forecast to return to West Michigan, and with the cool-down will come chances for waterspouts on Lake Michigan.
A waterspout is a rotating column of air and mist that occurs over a body of water. There are two different kinds of waterspouts: tornadic waterspouts and fair-weather waterspouts.
A tornadic waterspout is associated with a parent thunderstorm. These can move from land to water. This kind of waterspout is less common but often more destructive than a fair-weather waterspout. With a tornadic waterspout, the funnel develops from the thunderstorm and travels downward until it reaches the surface of the water and becomes a waterspout.
A fair-weather waterspout is more common and less dangerous. These form over warm waters as cooler air moves above. The cool air over the warm lake allows moist, warm air to rise and condense, forming clouds. Wind shear, or changing wind direction with height, then allows for the rising air to spin. In a fair-weather waterspout, the vortex develops at the surface and climbs up to the base of cumulus clouds above.
Fair-weather waterspouts typically move over the water at about 10 to 15 knots. They usually only last a few minutes before dissipating, though they can last as long as 20 minutes. If a fair-weather waterspout makes it to land, it typically dissipates quickly and does not produce damage as significant as a tornado. Still, they can be dangerous, and the National Weather Service would likely issue a Tornado Warning if a waterspout was about to make landfall.
Waterspouts are most common on the Great Lakes in the late summer and early fall when water temperatures are at their warmest. If you’re by the lakeshore next week, keep your eyes open! The combination of warm lake waters and cooler air moving into West Michigan will give us a good chance of seeing some waterspouts.