THE main area of interest in climatic indicator developments in recent weeks has been in the Indian Ocean.
This is especially the case in the long term (months) with increasing likelihood that the Indian Ocean Dipole will be negative for much of winter and early spring at least.
In addition, long range climatic models are suggesting the potential for another cool neutral or weak La Nina event in the Pacific Ocean by mid to late spring, although the situation in both oceans remains somewhat complicated.
Winter rainfall in NSW can be influenced by the Indian Ocean especially.
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This is because most weather systems in winter tend to move from west to east meaning that the Indian Ocean tends to play a more significant role in rainfall.
Over large parts of the Indian Ocean, sea surface temperatures remain above average.
During June, that pattern has continued to develop and the waters off the east coast of Africa have cooled slightly over a broad area and this is helping to create a negative IOD event.
It seems unlikely that an overly strong negative IOD event will occur given that the patterns in the Indian Ocean aren't classic with large areas of the ocean remaining warm.
But the patterns appear sufficient to generate an increase in rainfall potential for south east Australia, including southern Queensland, as this moisture gets drawn across in cloud bands by frontal systems.
In order for the moisture to be transported across to south east Australia it needs the large Southern Ocean fronts to occur.
When there are periods of more active or stronger fronts we should see more moisture flow down and this will help generate the potential for average to above average rainfall to occur, especially on and west of the ranges.
As we move into spring the impacts of the Pacific Ocean will gradually begin to play a more significant role in rainfall. Recent modelling has suggested the potential for a neutral to weak La Nina event to emerge by late spring.
However, it's too early to look at this with any confidence and such a development seems more likely than the reverse (El Nino) of which there is no sign of future development.
The Pacific Ocean will remain in a neutral state during the next two to three months in any case.
Even if a weak La Nina did re-develop, its impacts are unlikely to be felt until quite late in the year given there is no indication of a La Nina as it currently stands in the oceanic temperature patterns.
So in summary, the signs from both oceans give some cause for optimism for the rest of 2021.
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