Seasonal climate summary southern hemisphere (autumn 2007): La Niña a distinct possibility in 2007

Southern hemisphere circulation patterns and associated anomalies for the austral autumn 2007 are reviewed, with emphasis given to the Pacific Basin climate indicators and Australian rainfall and temperature patterns. Of primary interest in autumn 2007 was the return of the Southern Oscillation Index and Niño region sea-surface temperatures to neutral or near-neutral conditions, confirming the end of the 2006/07 El Nino event. The 20°C thermocline in the equatorial Pacific was closer to the surface during autumn, indicating the possible development of a La Niña later in the year. In the Australian region, tropical cyclone activity brought heavy rain to the northwest of Western Australia and parts of inland Australia. Otherwise, severe drought conditions persisted in the southwest of Western Australia and the MurrayDarling Basin. Warmer than average temperatures occurred throughout the eastern half of the continent.