|National Seasonal Rainfall Outlook: probabilities for May to July 2006, issued 21st April 2006|
50:50 chances for above average seasonal rainfall
The current seasonal rainfall odds do not strongly favour either wetter or drier than average conditions. Therefore, the chances of accumulating at least median rain during the late autumn to mid-winter period (May-July) 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 May to July period, the chances of above median rainfall are mainly between 45 and 55% across Australia, apart from 40 to 45% chances in Tasmania, parts of SA, Victoria and southern WA, and 55 to 60% chances in eastern NSW and southeast Queensland (see map).
So in years with ocean patterns like the current, about five May to July periods 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 the May-July period, history shows this effect to be moderately consistent in a band from the central Northern Territory across most of the southern two-thirds of Queensland, as well as the north-eastern half of New South Wales. Moderate consistency is also evident in much of Tasmania, parts of southern Victoria, and patches through the interior of Western Australia. Elsewhere the effect is only weakly or very weakly consistent (see background information).
The Southern Oscillation Index (SOI) has continued to fluctuate with a value of +14 in March following the reading of zero in February. The approximate SOI for the 30 days ending 17th April was +19. For more information on the SOI and the current status of ENSO, please 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, 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 25th MAY 2006