|Northern Aust Seasonal Rainfall Outlook: probabilities for May to July 2009, issued 24th April 2009|
Higher seasonal rainfall favoured in southern Qld and central NT
The northern Australian outlook for total rainfall over the May to July period shows a moderate shift in the odds favouring a wetter than normal season in southern Queensland and parts of central Northern Territory.
This pattern of seasonal rainfall odds is mainly a result of warm conditions in the Indian Ocean in January and March; the Pacific Ocean had little contribution to this forecast.
For the May to July period, the chance of exceeding median rainfall is between 60 and 70% in a region covering most of southern Queensland (see map). This means that for every ten years with ocean patterns like the current, about six or seven years are expected to be wetter than average over these parts, while about three or four years are expected to be drier. In addition parts of the central NT also have 60 to 65% chances of a wetter than normal three months, although some of this region is seasonally dry at this time of year.
Across the remainder of the region, the chance of exceeding the median rainfall during the coming three months is between 40 and 60%, meaning that above average falls are about as equally likely as below average falls in these regions.
New: Under the WATL part of the Bureau's website, there is an expanded set of seasonal rainfall outlook maps and tables, including the probabilities of seasonal rainfall exceeding given totals (e.g. 200 mm).
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. Elsewhere the effect is only weakly or very weakly consistent (see background information).
Pacific climate patterns are currently neutral and the consensus from computer models is for near average tropical Pacific surface temperatures in the middle of the year, although with some warming from present values. The SOI is approximately +8 for the 30 days ending 21 April. 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 detailed forecast maps, including the probabilities of seasonal rainfall exceeding given totals, can be found here.
More information on this outlook is available by contacting the Bureau's Climate Services sections in Queensland and the Northern Territory at the following numbers:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 26th May 2009