BOM La Niña likely near its end
BOM, 28 Feb 2023
La Niña has weakened in the tropical Pacific Ocean and is likely near its end. Ocean indicators of La Niña have returned to neutral levels, while atmospheric indicators that remain at La Niña levels have started to weaken.
All but one of the surveyed international climate models suggest sea surface temperatures in the tropical Pacific (including NINO3.4) will remain neutral (neither El Niño nor La Niña) through autumn; one model is neutral in March and April but touches on El Niño thresholds in May. ENSO outlooks extending beyond autumn should be viewed with caution as models typically have lower forecast accuracy at this time of year.
The Southern Annular Mode (SAM) index is currently positive, but is expected to return to neutral values over the coming weeks.
Warmer than average sea surface temperatures persist around south-east Australia, New Zealand and the west coast of Australia, but have returned to close to average temperatures in waters to Australia’s north.
The Indian Ocean Dipole (IOD) is neutral and has little influence on Australian climate while the monsoon trough is in the southern hemisphere (typically December to April). Forecasts for the IOD made at this time of the year have low accuracy beyond April.
Climate change continues to influence Australian and global climates. Australia’s climate has warmed by around 1.47 °C over the period 1910–2021. Southern Australia has seen a reduction of 10 to 20% in cool season (April–October) rainfall in recent decades.
Indian Ocean
The Indian Ocean Dipole (IOD) is currently neutral. The IOD typically has little influence on Australian climate while the monsoon trough is in the southern hemisphere (typically December to April). The IOD index value for the week ending 26 February 2023 was +0.16 °C; within neutral bounds (between −0.40 °C and +0.40 °C).
Sea surface temperatures (SSTs) are generally close to average across the tropical Indian Ocean, although there are weak warm SST anomalies present around the west coast of Australia.
Most international climate models surveyed by the Bureau anticipate neutral values of the IOD index will continue through the southern hemisphere autumn, although two models forecast the positive IOD threshold to be exceeded in May. While some models suggest positive IOD values may emerge during winter, IOD forecasts made at this time of the year have low accuracy when forecasting through the autumn.
Source: http://www.bom.gov.au/climate/enso/index.shtml#tabs=Overview
