A pulse of the climate phenomenon the Madden Julian Oscillation (MJO) in waters to the north of Australia over the coming week could act to further slow the onset of the El Nino event forecast by many climate agencies.
The Bureau of Meteorology (BOM) this week said in its Tropical Climate Update that climate models it was following suggested an MJO pulse is forecast to strengthen and move over the eastern Indian Ocean or western Indonesia in the coming week.
While the MJO is unlikely to have increased activity in the north-west Pacific, recently a pulse of the equatorial Rossby wave, a phenomenon that sees large horizontal atmospheric waves found in high-altitude wind, may have enhanced conditions in favour of increased tropical activity as it passed over the region in late August-early September.
Most models surveyed by BOM indicate the coming MJO pulse will then likely track eastwards into the eastern Indonesia but weaken by mid-September prior to re-entering the Western Pacific region.
How the MJO plays out while over Indonesia could have a critical role in what happens in the Pacific Ocean where El Nino events form.
A pulse over the Indonesia typically strengthens trade winds across the central Pacific, potentially further stalling development of an El Nino.
However, the BOM said it is unlikely to have an impact on the other side of the nation.
Based on current model guidance, which indicates the MJO pulse will weaken before moving into either the western Maritime Continent or Western Pacific region, there is unlikely to be a significant influence on wind strength over the equatorial Indian Ocean.
This means there is unlikely to be significant influence on the development of the Indian Ocean Dipole (IOD).
Most modelling is forecasting an IOD positive event forming, consistent with drier than average conditions over many parts of the country.