Abstract Two cases of east coast cyclogenesis are compared. They occur under weak and strong synoptic scale forcing, respectively. A set of objective analyses with one degree latitude-longitude horizontal resolution and 100 mb vertical resolution is used to support the diagnostic analysis. A more limited subjectively prepared data set is used as a check against the objective analyses. Vertical motions are computed from a diagnostic ten-level nonlinear balance model. The vertical motions are partitioned into contributions from latent heat release, thermal advection and differential vorticity advection. Energetics, after Lorenz, are computed from the balanced vertical motions. One of the principal results is that thermal advection and latent heat release are both of nearly equal importance to low level convergence and vorticity production for the weak cyclone event, while differential cyclonic vorticity advection in addition is crucial to the deeper, more intense development. The kinematic analysis disclose...