Keyser This project involves investigations of selected aspects of the dynamics of extratropical baroclinic wave regimes, all of which will contribute to a better understanding of the process of extratropical cyclogenesis. The research will consist of both diagnostic and numerical modeling studies. Three principal activities to be undertaken are (1) analyses of ageostrophic circulations in the vicinity of upper level jet streaks and frontal zones, (2) a study of the nature of upper level precursors of cyclogenesis and the applicability of vortex dynamics, and (3) a study of the dynamics and evolution of atmospheric jet streaks using a hierarchy of numerical models. The principal investigator's view of jet streak dynamics, in particular, is quite different from the conventional view and, if shown to be correct, would radically change the atmospheric sciences community's understanding of jets. This research is important in improving understanding of the development of midlatitude storms. ***