Seasonal climate summary southern hemisphere (summer 1989-90): weak warming in the western equatorial Pacific and an inactive Australian monsoon

A climate analysis is presented of the southern hemisphere circulation for the austral summer, December 1989 to February 1990, with a more detailed treatment of the Australian region. A weak warming in the western equatorial Pacific, a fall in the Southern Oscillation Index and shifts in other climate indices were indicative of a weak El Niño situation. Inactive monsoonal conditions in the Australian region were related to a split in the Walker Circulation, which was compatible with a weak El Niño situation. Record low rainfall occurred in extensive parts of north and northeast Australia for the three-month period. In mid-latitudes a strong four-wave planetary pattern was dominant and the polar vortex was weak.