|National Seasonal Rainfall Outlook: probabilities for July to September 2004, issued 17th June 2004|
Increased falls more likely in parts of Qld & WA for September quarter
There is a moderate shift in the odds towards above average three-month falls in north Queensland and small parts of southwest WA, the Bureau of Meteorology announced today. For most of the country, including the parts of NSW, SA and Victoria that have been very dry recently, the shifts in the odds are too weak to offer any firm guidance as to the most likely outcome for September quarter rainfall.
However, even near average rainfall in the southeast of the country during the coming three months, will only raise the year-to-date total to somewhere near the tenth percentile. In other words, 90% of years would still be wetter.
The current pattern of outlook probabilities has been mostly influenced by recent temperature patterns in the Pacific Ocean.
For the July to September period, the chances of above median rainfall are between 60 and 65% in some small areas in southwest WA, and over parts of northeast and north Queensland north of Rockhampton (see map). So in years with ocean patterns like the current, about six September quarters out of ten are expected to be wetter than average in these parts of the country, with about four out of ten being drier.
However, it should be noted that July to September is the heart of the dry season across northern Australia and heavy rain is uncommon during this period.
Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During July to September, history shows this influence to be moderately consistent across most of Queensland and the NT, large parts of NSW and SA, but generally weakly consistent elsewhere across the country, reaching moderate only in patches (see background information).
Both the Indian and tropical Pacific Oceans remain mostly warmer than average, although both cooled between April and May. For more detail see the the El Niño Wrap-Up.
The Southern Oscillation Index (SOI) rebounded strongly in May to a value of +13, 28 points above April's 15. The approximate SOI for the 30 days ending 14th June was +7.
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, Felicity Gamble on (03) 9669 4256|
|Regional versions of this media release are available: | Qld
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 13th JULY 2004.