THE current La Nina event is still dominant, despite peaking in strength about a month ago.
However, across the western tropical Pacific, the south-east trade winds continue to be stronger than normal (typical of a La Nina event) and this appears to have delayed any further weakening of the La Nina in recent weeks.
As a result, modeling now indicates a return to neutral El Nino-Southern Oscillation (ENSO) levels is likely to be delayed until later in autumn.
Nevertheless, as noted previously, even a weakening La Nina will continue to influence our climate patterns.
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Apart from the stronger than normal trade winds, other atmospheric and oceanic indicators over the Pacific persist at La Nina levels.
In the atmosphere, the other indicator remaining at La Nina levels is the decreased cloudiness along the date line. There is also a strong positive Southern Oscillation Index (SOI).
The current 30-day running mean has increased again in the past week and is currently around +12, well into the La Nina range.
In the eastern tropical Pacific, the warming trend in sub surface waters that was evident from late January, and which is often an early indicator of the breakdown of the La Nina, has stalled in the last couple of weeks.
This is another factor in now believing this La Nina event will persist for at least another one to two months.
After that, there is still a consensus that neutral outlooks are favoured for most of the remainder of the year with the chances of another La Nina most unlikely statistically but still an outside possibility.
With warmer ocean temperatures across the world creating a new set of parameters due to global warming, the third La Nina cannot be ruled out.
To the north, the Madden-Julian Oscillation (MJO) is still weak in the Australian region and is likely to remain weak for at least another week or so.
However, it appears that a pulse of the MJO is strengthening over the eastern Indian Ocean. Most climate models suggest the MJO is likely to move into Australia's north in the coming week.
When this occurs there is also an increased chance of some tropical moisture finding its way further south in eastern Australia, especially in conjunction with the La Nina set up. This could be the final pulse of the season.
To the west and south both the Indian Ocean Dipole (IOD) and the Southern Annular Mode (SAM) continue to be neutral and as such will have little or no influence on south-east Australia's rainfall patterns in the coming month or so.
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