We perform visualization of the nullcline dynamics around threshold, and characterize important geometric properties via dominant scale analysis, which avoids the need to make asymptotic approximations. In particular, we analyze the transient dynamics during the passage through the ghost of a saddle-node bifurcation in the (V, m) phase-plane projection of a local 3D approximation to the 4D H-H equations (where sodium inactivation h is held constant).