Tornado with Subvortex Filaments
(Part 2 of 3) Wide-angle view as the tornado continued moving ENE toward the Cimarron River south of Dover. Note the skirt of scud wrapping into it at cloud base, and the well-defined slot of brightness to its upper right (to its NW). So-called "clear slots" like this -- which may just be less cloudy -- are common with tornadoes from classic supercells. They are evaporated out of the clouds by sinking, drying air in the occlusion downdraft wrapping through the parent mesocyclone. Look closely at the bottom of the visible funnel to see a couple of small strands of cloud material. These were actually sub-vortices within the tornado, orbiting its circulation center at high speed. Multiple vortex structures such as this are quite common in tornadoes -- even some small ones. They account for the cycloidal (overlapping-coil shaped) scour marks often seen from the air when flying over a fresh tornado track.
5 WSW Dover OK (4 Oct 98), looking SE