This was the classic situation where two big storms merge to form a monster. It took almost the same path as the supercell back in April 1996 except this storm traveled from as far as northern Oklahoma. Thats a very long time for a storm complex to stay together. The March 12 2006 supercell produced an EF-2 tornado that hit in Springfield Illinois causing major damage. Tornadoes were also reported in other parts of Sangamon County, Greene County, Morgan County, Logan County, Scott County, northwest Macon County and southern Dewitt County. This historic storm layed its mark on Central Illinois.
Check out fellow chaser Paul Hadfield with the only known images of the storm as it clipped northwestern Macon County.
http://www.pawleewurx.com/pmh/031206.html