The use of indices in following the trend in surface synoptic patterns - in particular, as indicating the possibility of the persistence of a large quasi-stationary trough south of Australia

Indices of the westerly. surface circulation from 35-50°S and 40-175°E were plotted as running five day means, as allso that at the 300 mb level, over the Australian area from 115-165°E; for the latter, the mean strength of the jet stream was used as an index. Peak values of both indices were found to coincide with the occurrence of a large quasi stationary trough south of the Continent.