We derive the Kramers-Moyal equation for the conditional probability densit
y of velocity increments from the theoretical model recently proposed by V.
Yakhot [Phys. Rev. E 57, 1737 (1998)] in the limit of the high Reynolds nu
mber. We show that the higher order (n greater than or equal to 3) Kramers-
Moyal coefficients tend to zero and the velocity increments are evolved by
the Fokker-Planck operator. Our results are compatible with the phenomenolo
gical description, developed for explaining recent experiments by R. Friedr
ich and J. Peinke [Phys. Rev. Lett. 78, 863 (1997)].