Seasonal Climate Outlook - June 2011 to August 2011
The Bureau of Meteorology released its rainfall outlook for June to August 2011 on 24 May. The outlook reports that, for Victoria, below average winter rainfall is just as likely as above average winter rainfall. A wetter than average season is expected for the northern Murray-Darling Basin.
The Bureau’s latest ENSO Wrap-Up, issued on 25 May, reports that the 2010/11 La Niña event has ended, with most indicators having returned to average levels. All available climate models indicate continuous warming of the Pacific Ocean in the coming months, with neutral conditions likely to persist through winter.
After lagging for several months, atmospheric indicators of ENSO such as pressure patterns, cloudiness and the trade winds, have responded to warming in the Pacific Ocean. The warming in the Pacific Ocean and changes in the atmosphere are consistent with the life cycle of past La Niña events, most of which lasted 9-12 months before declining during the southern autumn.
The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is currently neutral. However, a weakly positive IOD event has been forecast to develop during winter. Positive IOD events in the past have been associated with drier conditions over south-east Australia during the winter and spring months.