Seasonal climate summary southern hemisphere (autumn 1999): a decline in weak cold episode conditions in the tropical Pacific

Southern hemisphere circulation patterns and anomalies for autumn 1999 (March – May) are reviewed, with emphasis given to the tropical Pacific and the Australian region. The subsurface ocean structure through the equatorial Pacific, as shown by the depth of the 20°C isotherm, indicated that the weak Pacific cool event was over. The sea-surface temperature pattern tended toward neutral conditions during autumn, and atmospheric indicators, although somewhat lagging the subsurface and surface ocean indicators, were consistent in showing a trend toward normal conditions. Widespread heavy rainfall and record surface wind speeds in western areas of Australia were associated with tropical cyclone activity in early to mid-autumn. An active monsoonal trough in March and April brought above average rainfall to northern Australia. Daytime temperatures were generally lower over parts of western and eastern areas and higher through central Australia.