Recent and past observations of a central downdraft within a mesocyclone ha
ve been misinterpreted as evidence of vortex breakdown on the mesocyclone s
cale. In this note, the literature is reviewed and model examples are provi
ded in order to demonstrate that the mesocyclone dynamics likely precludes
mesocyclonic vortex breakdown. It is shown that an adverse vertical pressur
e gradient, induced by vertical vorticity that decreases in intensity with
height, leads to the formation of a central downdraft, hence, two-celled vo
rtex, in absence of vortex breakdown. Two-celled mesocyclones, then, may fo
rm when low-level vertical vorticity, exceeds that generated at midlevels.
Tornadogenesis occurs in a two-celled mesocyclonic vortex if an instability
to which the vortex is susceptible is released.