Hail and Damaging Winds in Michigan, July 24, 1999

An upper level disturbance crossed the Great Lakes region from northwest to southeast, igniting thunderstorms along its path. The thunderstorms evolved into a squall line as they moved across southeast Michigan. Instability was high on this warm and humid summer day, allowing many of the storms to become severe.Unlike the previous day, severe reports were almost evenly split between large hail and damaging wind. Most of the damaging wind gusts took down trees, tree limbs, utility poles, and power lines. However, the marine community felt the brunt of the severe thunderstorm winds in two separate incidents. A large number of sailboats were returning to the Bay City Yacht Club after a competition on Saginaw Bay, when the line of storms struck. As many as a dozen boats were capsized, with two sailboats demasted. On Lake St Clair, wind gusts capsized one sailboat, and caused a cabin cruiser to run aground.The largest hail of the day, golfball sized, was reported in Kawkawlin, Bay City, Zilwaukee, and Southfield. In Bay City, the large hail fell on the exposed mariners (see above), causing welts and bruises to at least two.