A diagnostic analysis of two intense monsoon depressions over Australia.

Abstract

For each situation, the Northern Hemisphere circulation becomes favorable well prior to genesis. The short-term trigger for development is the strengthening of the Southern Hemisphere subtropical ridge at the surface and an amplifying upper-level trough and subtropical jetstreak to the SW of the formation point. The outer region structure of these monsoon depressions is remarkably similar to that of a tropical cyclone, even though the systems develop over land. During development, maximum convective heating occurs at middle levels and within a region of already high cyclonic vorticity. Evidence suggests that the cloud population is mostly comprised to deep cumulonimbus clouds, middle-level stratiform cloud and shallow cumulus.-from Authors