  We analyze the evolution of hydrodynamic fluctuations in a heavy ion
collision as the system passes close to the QCD critical point. We introduce
two small dimensionless parameters $\lambda$ and $\Delta_s$ to characterize the
evolution. $\lambda$ compares the microscopic relaxation time (away from the
critical point) to the expansion rate $\lambda \equiv \tau_0/\tau_Q$, and
$\Delta_s$ compares the baryon to entropy ratio, $n/s$, to its critical value,
$\Delta_s\equiv (n/s - n_c/s_c)/(n_c/s_c)$. We determine how the evolution of
critical hydrodynamic fluctuations depends parametrically on $\lambda$ and
$\Delta_s$. Finally, we use this parametric reasoning to estimate the critical
fluctuations and correlation length for a heavy ion collision, and to give
guidance to the experimental search for the QCD critical point.
