Southern Hemisphere Application of the Systematic Approach to Tropical Cyclone Track Forecasting. Part I: Environmental Structure Characteristics

Abstract

The environment structure conceptual models of the Systematic Approach to Tropical Cyclone Track Forecasting technique of Carr and Elsberry are applied to all Southern Hemisphere tropical cyclones during January 1994 - June 1997. Whereas three of the four synoptic patterns from the western North Pacific could be applied with relatively small modifications, a new High (H) amplitude synoptic pattern was defined to classify the situations with large meridional penetrations of mid-latitude troughs deep into the Southern Hemisphere tropics. Some changes in terminology were required to describe the synoptic regions that have characteristic track directions. All 1592 cases during the period could be described by these four synoptic patterns and 11 synoptic regions. Important track changes were found to be associated with transitions between these synoptic patterns and regions. Three binary tropical cyclone interactions defined for the Western North Pacific were adapted for use in the Southern Hemisphere with considerable success. A preliminary climatology of occurrences for the synoptic pattern/region combinations, ions, transitions between combinations, and binary tropical cyclone interactions are calculated. Sequences of synoptic analyses related to these transitions are described to aid in theapplication.