July 23, 2008


Danger of drought in eastern Australia passes


The impact of the combined influences of the Pacific and Indian oceans suggest that winter crops including wheat in Eastern Australia can look forward to average rainfall in coming months, according to the Australian government's Bureau of Meteorology.


The bureau previously identified a positive mode for the Indian Ocean Dipole (IOD) as a key influence for a drought in 2007 that wrecked winter crops including wheat in Southeast Australia.


A positive mode for the IOD is an effect that often hinders the formation of the northwest cloudbands that are an important source of winter/spring rainfall in southeast Australia.


While most climate models for the Pacific Ocean show a continuation of neutral conditions, a small chance remains that an El Nino weather pattern will develop in 2008, the Bureau said.


The majority of dynamic computer models predict neutral conditions to continue in the eastern to central Pacific in the coming months, but two predict Pacific temperatures above the El Nino threshold by September, it said.


An El Nina pattern is usually associated with below average rainfall in eastern Australia.


The bureau also said that an IOD is in a positive phase "but the index used to measure the IOD has weakened considerably since its peak in early June."


Those models that forecast the IOD show it persisting but moderating further throughout the rest of the year, the bureau said in a regular statement reviewing macro influences on Australia's climate.


The bureau's Southern Oscillation Index remains neutral, posting a value of +3 in the 30 days ended July 21, compared with +4 in June and -4 in May.


The bureau's next update of La Nina/El Nino indicators and the IOD is scheduled by Aug. 13.


Estimates for national wheat production in 2008 are mostly in a range between 20 million and 25 million tonnes. Production from a drought-affected crop in 2007 reached just 13 million tonnes.

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