Lake Michigan Waterspout Forecast
A refreshing cold front will arrive tonight into Saturday allowing temperatures to fall back into the low to middle 70s at the surface. Colder air aloft will be present as a trough moves overhead. That trough is important because it could help to spawn waterspouts over lake Michigan.
The International Centre for Waterspout Research has a computer model that helps to forecast waterspouts over the Great Lakes. Their model is showing an elevated risk for waterspouts over the open waters of Lake Michigan on Saturday.
Fair weather waterspouts form over open water. They develop at the surface of the water and climb skyward in association with warm water temperatures and high humidity in the lowest several thousand feet of the atmosphere. They are usually small and relatively brief.
Waterspouts occur most frequently during the months of August, September, and October, when the waters of the Great Lakes are near their warmest levels of the year. Waterspout formation typically occurs when cold air moves across the Great Lakes and results in large temperature differences between the warm water and the overriding cold air. The surface lake waters are running in the upper 60s and lower 70s. You compare that to very cold air aloft, and you have plenty of instability over the waters. They tend to last from about two to twenty minutes, and move along at speeds of 10 to 15 knots.