Factors which influence the development of a low-level jet and coastal cyclogenesis

Mesoscale model simulations were run to examine the mechanisms which generate a low-level jet (LLJ) and the sea-level pressure decrease (SLPD) associated with secondary cyclogenesis along the East Coast of the U.S. Data collected during the Presidents' Day cyclone of February 18-19, 1979 are reviewed, including the behavior of the LLJ preceding cyclogenesis. The simulations covered adiabatic conditions, the absence and presence of latent heating, and the inclusion of all physical parameters with and without computations of boundary layer phenomena, 60-km grid-scale precipitation, and convective precipitation. The results indicate that synergistic reactions among the LLJ, latent heat release, jet-induced circulation, and boundary layer processes are necessary to account for secondary cyclogenesis and the accompanying rapidly evolving mass, momentum and moisture fields.