|National Seasonal Rainfall Outlook: probabilities for November 2005 to January 2006, issued 18th October 2005|
Above average seasonal falls a 50:50 prospect
The chances of accumulating at least median rain during the late spring to mid-summer period (Nov-Jan) 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 November to January period, the chances of above median rainfall are between 40 and 45% in parts of eastern Australia, and between 55 and 60% across parts of northern and central Australia (see map). These are the largest departures from 50:50.
So in years with ocean patterns like the current, about five November to January periods 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 the November to January quarter, history shows this influence to be moderately consistent across much of Tasmania, NSW, Queensland and the NT, but generally weakly consistent elsewhere (see background information).
The Southern Oscillation Index (SOI) has fluctuated about zero during recent months with values of +1 in July, −7 in August and +4 in September. The approximate SOI for the 30 days ending 15th October was +4.
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, Blair Trewin on (03) 9669 4603, David Jones on (03) 9669 4085.|
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 16th NOVEMBER 2005