Seasonal climate summary southern hemisphere (winter 2012): dry conditions return to Australia

Southern hemisphere circulation patterns and associated anomalies for austral winter 2012 are reviewed, with an emphasis on Pacific Basin climate indicators and Australian rainfall and temperatures. Winter 2012 saw warm conditions in the equatorial Pacific that failed to reach sustained El Nino criteria, with sea surface temperatures in the NINO3 region close to El Nino thresholds but near-neutral values in atmospheric-based indices. The Southern Annular Mode entered a positive phase during July and a positive Indian Ocean Dipole event emerged during August. The combination of these phenomena led to drying conditions across southern Australia during winter and the emergence of severe rainfall deficiencies in Western Australia and South Australia. Maximum temperatures were close to normal during winter for most of Australia, although warmer than average for Western Australia. August was warmer than average across the continent, with especially warm conditions developing in Western Australia. Minimum temperatures were well-below average across the country, associated with southerly wind anomalies in central Australia.