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Dear Tom,
How high do waves on Lake Michigan ever get?
—Ronald Pellagrin, Chicago
Dear Ronald,
Waves (other than tsunamis or other non-wind produced waves) are generated by wind blowing across water for a period of time. The stronger the wind, the longer the expanse of water (the fetch) and the longer the duration of wind, the higher the waves will be. On the open ocean, where the fetch can be several thousand miles, wave heights can exceed 50 feet, and even approach 100 feet in intense storms. Waves heights on the Great Lakes are much less. Lake Superior, the largest of the Great Lakes, experiences the highest waves – about 30 feet. Forecasters at the National Weather Service Romeoville office say the highest waves on Lake Michigan are 20 to 23 feet in height.v