|National Seasonal Rainfall Outlook: probabilities for Summer 2005/2006, issued 16th November 2005|
50:50 chances for a wetter than average summer
The chances of accumulating at least median rain during summer (Dec-Feb) are close to 50% across the entire country, the Bureau of Meteorology announced today. The outlooks are based on relationships between Pacific and Indian Ocean temperatures and Australian rainfall. Recent ocean temperatures have not been sufficiently warmer or cooler than average to produce a strong bias in rainfall outlook odds.
For the December to February period, the chances of above median rainfall are between 55 and 60% through much of New South Wales and parts of SA and northern Victoria, and between 45 and 55% across remaining parts of Australia (see map).
So in years with ocean patterns like the current, about five summers out of ten are expected to be wetter than the median over Australia, with about five out of ten being drier.
Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During summer, history shows this influence to be moderately consistent across much of WA and scattered areas in eastern Australia, but generally weakly or very weakly consistent through the centre of the country (see background information).
The Southern Oscillation Index (SOI) has risen steadily over the past few months with values of −7 in August, +4 in September and +11 in October. The approximate SOI for the 30 days ending 13th November was +8.
For routine updates on the latest data relating to El Niño, together with details on what the phenomenon is and how it has affected Australia in the past, see the ENSO Wrap-Up.
Click on the map above for a larger version of the map. Use the reload/refresh button to ensure the latest forecast map is displayed.
|The following climate meteorologists in the National Climate Centre can be contacted about this outlook: Grant Beard on (03) 9669 4527, Andrew Watkins on (03) 9669 4360.|
Regional commentary is available from the Climate and Consultancy Sections in the Bureau's Regional Offices:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 19th DECEMBER 2005