This loop of GOES-8 visible imagery shows the development of convection which produced a tornado that struck Siren, Wisconsin (station identifier KRZN) around 01:20 UTC on 19 June (8:20 PM CDT on 18 June) 2001. The tornado initially touched down around 01:06 UTC (8:06 PM CDT) approximately 10 miles west of Siren, and continued to travel east to about 14 miles east of Siren.

Note the appearance of multiple cloud bands oriented N-S across east-central Minnesota into northwestern Wisconsin prior to convective development. These roll clouds within the boundary layer indicated the presence of a shallow stable layer left over from convective outflow boundaries earlier in the day.