La Niña has ended, with signs of drier weather coming

Sheep Central, March 15, 2023

THE recent La Niña oceanic and atmospheric phenomenon has ended and there are signs an El Niño could form later in the year, the Bureau of Meteorology has reported in its latest Climate Driver update.

La Niña is an oceanic and atmospheric phenomenon that is the colder counterpart of El Niño, as part of the broader El Niño–Southern Oscillation climate pattern.

The bureau said La Niña has ended in the tropical Pacific Ocean. The El Niño–Southern Oscillation (ENSO) is now neutral (neither La Niña nor El Niño) with oceanic and atmospheric indicators having returned to neutral ENSO levels, it said.

The bureau said international climate models suggest neutral ENSO conditions are likely to persist through the southern Autumn. However, there are some signs that El Niño could form later in the year. Hence, the bureau has issued an El Niño Watch. This means there is around a 50 percent chance of an El Niño in 2023.

The Madden–Julian Oscillation (MJO) is currently very strong over the Pacific Ocean but is forecast to move into the Atlantic Ocean in the coming fortnight. This may bring drier conditions to Australia for the latter half of March, the bureau said.

The Southern Annular Mode (SAM) index is currently strongly negative but is expected to return to neutral values over the coming week.

The bureau said warmer than average sea surface temperatures persist around south-east Australia, New Zealand and the west coast of Australia, but close to average temperatures prevail around northern Australia.

The Indian Ocean Dipole (IOD) is neutral – the IOD typically 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.

The bureau said climate change continues to influence Australian and global climates. Australia’s climate has warmed by around 1.47 °Celsius over the period 1910–2021. There has also been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially across northern Australia. Southern Australia has seen a reduction of 10 to 20pc in cool season (April–October) rainfall in recent decades, the bureau said.

Source – Bureau of Meteorology.


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