  We identify a sufficient condition under which solutions to the 3D forced
Navier--Stokes equations satisfy an $L^p$-in-time version of the Kolmogorov 4/5
law for the behavior of the averaged third order longitudinal structure
function along the vanishing viscosity limit. The result has a natural
probabilistic interpretation: the predicted behavior is observed on average
after waiting for some sufficiently generic random time. The sufficient
condition is satisfied e.g. by the solutions constructed by Bru\`e, Colombo,
Crippa, De~Lellis, and Sorella. In this particular case, our results can be
applied to derive a bound for the exponent of the third order absolute
structure function in accordance with the Kolmogorov turbulence theory.
