Seasonal climate summary southern hemisphere (summer 1990-91): a strong Australian monsoon with record rainfall

A climate analysis is given of the southern hemisphere summer circulation, December 1990 to February 1991, with more detailed treatment of the Australian region. A strong monsoon occurred in the Australian region with record high summer rainfall over extensive areas of northern Australia and major floods. Positive sea-surface temperature anomalies expanded in the western equatorial Pacific and in the equatorial Indian Ocean, whereas negative anomalies were noted in an area off the coast of Peru. An extensive area of positive sea-surface temperature anomalies formed at mid-latitudes in the South Pacific. A four-wave planetary pattern was evident in the upper troposphere with an anomalously deep trough in the western Pacific and relatively weak troughs in the eastern Pacific, eastern Atlantic and Indian Oceans.