The 10 May 2004 Limon, Colorado tornadic event: An examination of a cyclic tornadic supercell in a weak upper level flow environment

During 10 May 2004, a supercell thunderstorm developed on the eastern Plain of Colorado. This storm went on to produce multiple tornadoes as it tracked northeast over the Palmer Divide, just to the west of Limon, Colorado. Radar analysis of this storm indicated obvious supercell characteristics, yet the large scale synoptic wind field environment did not support conditions favorable for a cyclic tornadic supercell storm. Wind fields at mid and upper levels on this day were forecast to be rather weak, and the DEN sounding at 00Z indicated such flow aloft (30 knots at 500 mb, 40 knots at 400 mb, 15 knots at 300 mb).

Examination of KFTG (Denver, CO) and KPUX (Pueblo, CO) indicated this storm did not become tornadic until it interacted with a westward moving boundary. It is believed that this boundary augmented the low level environmental shear producing an environment favorable for tornadic activity.