A supercell thunderstorm which produced a tornado in Iowa at 9:00 p.m. CT entered Wisconsin from the Iowa/Illinois border at midnight. At 12:30 a.m., the first tornado touched down in Lafayette County. At 12:41 a.m., the tornado drove through Barneveld. A sharp bolt of lightning as well as a loud clap of thunder cut the power to the city, awakening residents. Other tornadoes broke out before dissipating after 3:00 a.m. CDT.