MORE evidence of a developing El Niño event has emerged during the past fortnight, and computer forecasts show there's very little chance of the development stalling or reversing.
Responding to continued weak trade winds, equatorial sea-surface temperatures are now more than 1°C above normal in the eastern half of the Pacific, according to the Bureau of Meteorology.
Although the Southern Oscillation Index (SOI) has risen in the past fortnight, it remains below zero, at around -2.
The Bureau says a more complete picture of the situation in Pacific will be available next week when the final June indices are calculated.
Currently, the SOI has moved up into the neutral range (-5 to +5), having been below -5 for much of May-June.
According to the Bureau, when it consistently records values above or below the neutral -5 to +5 range for two months or more, a definite trend is considered established.
El Niño events are usually (but not always) associated with below normal rainfall in the second half of the year across large parts of southern and inland eastern Australia.
Another adverse sign for southeastern Australian rainfall is the recent trend to positive values in the Indian Ocean Dipole (IOD), as measured by the Dipole Mode Index (DMI).
All international dynamic computer models surveyed by the Bureau of Meteorology predict further warming of the Pacific Ocean sea surface temperature (SST) in coming months.
All models predict SST to be above El Niño thresholds throughout most of the second half of 2009.
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