|National Seasonal Rainfall Outlook: probabilities for Autumn 2006, issued 21st February 2006|
50:50 chances for a wetter than average autumn
The chances of accumulating at least median rain during autumn (Mar-May) 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 March to May period, the chances of above median rainfall are mainly between 45 and 55% across Australia, apart from 40 to 45% chances in north Queensland and 55 to 60% chances in northwest WA (see map).
So in years with ocean patterns like the current, about five autumns out of ten are expected to be drier than the median over the country, with about five out of ten being wetter.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During autumn, history shows this effect to be moderately consistent across much of the north and west of the country. Elsewhere the effect is only weakly or very weakly consistent (see background information).
The Southern Oscillation Index (SOI) rose from +1 in December to +13 in January. The approximate SOI for the 30 days ending 18th February was +4. The recent positive SOI values are consistent with developments towards La Niña conditions in the Pacific Ocean. More information is available in the 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, David Jones on (03) 9669 4085, Blair Trewin on (03) 9669 4603.|
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 23rd MARCH 2006