Subsynoptic-Scale Structure in a Major Synoptic-Scale Cyclone

Abstract

Abstract An analysis of a major cyclone over the eastern United States in late February 1984 revealed the presence of several embedded well-defined mesoscale structures, including a low-level jet, a long-lived snowband and a strong upper-level front. Understanding the importance of these mesoscale features to the evolution of the synoptic-scale cyclone is the basis for this paper. Evidence is presented that a period of weakening after initial surface cyclogenesis was the result of decoupling of the upper-level trough from the surface cyclone, as a consequence of the development of peripheral mesoscale precipitation systems. Redevelopment on the western side of the Appalachians occurred where orographic subsidence was amplified by a strong mesoscale low-level jet. Further intensification then took place when a strong upper-level frontal zone approached the surface cyclone. An incidental finding is that one of the mesoscale precipitation systems was a snowband, driven by strong synoptic-scale frontogenetica...