At this stage, the Pacific Ocean El Nino event is continuing, although a steady weakening trend is evident in the sea surface temperatures and sub surface temperature patterns. Most international and local climate models indicate SSTs in the central tropical Pacific are expected to continue to decrease and therefore return to a neutral situation during the autumn months.
Subscribe now for unlimited access to all our agricultural news
across the nation
or signup to continue reading
Atmospheric indicators are not as clear cut but overall, they appear to be also indicating a weakening El Nino. In the tropics, cloudiness near the International Date Line has decreased in recent weeks. However, the 30-day running mean of the Southern Oscillation Index is around -8, which is still in the El Nino range. However, fluctuations in the SOI can be common during summer and are not an indication of El Nino strength.
International climate models suggest the central tropical Pacific Ocean will continue to cool in the coming months, with most forecasting neutral conditions by mid to late April and all predict neutral conditions in May. After that, things become less clear. Historically, around 50 per cent of El Nino events have been followed by a neutral year, and a little over 40pc have been followed by La Nina. Many reliable models out of the United States indicated the chance of a La Nina returning exceeds 60pc by late winter and peaks at 70pc during spring 2024.
However, global oceans have warmed significantly in recent years and have been the warmest on record globally between April 2023 and January 2024. (On March 8 the ocean temp off Sydney was 26.7 degrees - the highest ever recorded.) These changes may impact future predictions of ENSO events in ways that are unclear at this stage. In addition, ENSO predictions made in autumn tend to have lower accuracy than predictions made at other times of the year. This means that current forecasts of what could happen beyond May should be taken with a little caution.
The Indian Ocean is also warmer than it has ever been overall. The Indian Ocean Dipole is neutral at the moment but as mentioned previously, it has minimal effect on our rainfall patterns before April. There is equal divide between it staying neutral or drifting into the negative by early winter so its effects, if at all, will be towards at least occasional rain events at those times.
Finally, to the north the Madden-Julian Oscillation is in the eastern Indian Ocean and is expected to move into the Australian region in mid to late March with an increase in rainfall potential in the tropics initially. Subsequently, some moisture may eventually find its way south.
