The most tornadoes in a single day in Michigan occurred on May 21, 2001. A total of 19 tornadoes were confirmed in the state, including four separate tornadoes in Kent County. Across Lower Michigan, there were two EF2 tornadoes, 4 EF1 tornadoes and 13 EF0 tornadoes. Besides the tornadoes in Kent Co., tornadoes were also reported in Ottawa, Allegan, Barry, Kalamazoo, Eaton, Gratiot, Clinton, Ionia and Isabella Counties.
The map above is Severe Weather Reports on May 21 2001 in the U.S. Red dots are where tornadoes touched down, blue dots are wind damage and green dots are severe hail reports.
I remember the day well. I had a morning speech in Spring Lake. It was a gray morning with a low cloud deck, scattered showers and a cool east wind. There was a fairly sharp warm from coming north from Indiana and there was a quick windshift with the front from the east to the south. The first warning came out just as I came into the Weather Office. Here’s a summary of some of the tornadoes (lots of info at the liink).