|Southeastern Aust Seasonal Rainfall Outlook: probabilities for Winter 2008, issued 27th May 2008|
Above normal winter rainfall favoured for north-eastern NSW
The seasonal climate outlook for winter shows that higher than normal rainfall is favoured over the northeastern half of NSW. Elsewhere in southeastern Australia the odds are generally neutral.
The pattern of seasonal rainfall odds across the southeast is a result of higher than average temperatures in the Indian Ocean, and cooler than average waters in the central to western equatorial Pacific in association with the decaying La Niña pattern.
The chances of exceeding the median rainfall over winter are around 60% over the parts of NSW northeast of a line from about Sydney to close to the northwest corner of the state (see map). So for every ten years with ocean patterns like the current, about six winters are expected to be wetter than normal and four winters drier in these parts.
Over the rest of southeastern Australia the chances of wetter-than-average conditions for winter are about the same as drier-than-average conditions.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During winter, history shows this influence to be moderately consistent over most of southeastern Australia, but only weakly consistent over western Tasmania, much of SA and far southeastern NSW (see background information).
The 2007/08 La Niña event in the Pacific Basin has decayed to neutral conditions: computer models indicate a continuation of neutral conditions through the forecast period. The 30-day value of the Southern Oscillation Index (SOI) was −3 as at 24th May. For routine updates and comprehensive discussion on any developments 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.
More information on this outlook is available Monday to Friday from 9.00am to 5.00pm local time by contacting the Bureau's Climate Services sections in Queensland, NSW, SA, Victoria and Tasmania at the following numbers:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 26th June 2008