Seasonal Climate Outlook July - September 2007
The latest Seasonal Outlook issued by the Bureau of Meteorology on 26 June reports no strong swings towards either above-normal or below-normal rainfall in Victoria over the next three months. The chances of exceeding median rainfall for the July-September period are 40-45% in western Victoria, increasing to 50-55% in the east.
The chances for a warmer than average season are 55 and 60% across the State.
After stalling for about a month, there are renewed signs from the Pacific Basin that are consistent with the early stages of a La Niña event. The SOI has risen sharply from -2.0 to +12, the Trade Winds are much stronger than average and the cloud cover in the Pacific near the equator has been consistently below normal during June. In addition, the Pacific remains cooler than average and a persistence of Trade Winds should see this cooling intensify and spread westwards.
If, as all major international computer models predict, the Pacific continues to cool over the coming month, there is a distinct likelihood of a La Niña event occurring in 2007. If this occurs, subsequent climate outlooks are likely to indicate increased chances of above average rainfall over the eastern half Australia.
The Bureau will release its next seasonal outlook on 24 July 2007.