Australian Bureau of Meteorology, Climate Driver Update, 20 Dec 2022:
La Niña continues in the tropical Pacific, but some indicators show signs of declining strength. La Niña typically increases the chance of above average rainfall for northern and eastern Australia during summer. Models suggest that ocean temperatures may reach ENSO-neutral levels during January or February 2023, and remain at neutral levels until at least April. Model accuracy for lead times greater than four months is generally lower at this time of year than at other times, so outlooks beyond April should be viewed with caution.
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).
The Southern Annular Mode (SAM) is in a positive phase and is likely to be neutral to positive through January and February. During summer, a positive SAM increases the chance of above average rainfall for parts of eastern Australia and below average rainfall for western Tasmania.
The Madden–Julian Oscillation (MJO) is expected to move across the Maritime Continent and Western Pacific regions over the coming fortnight, which may lead to increased westerly flow and rainfall across parts of northern Australia. The influence of the MJO may lead to the onset of the Australian monsoon during this time, while also increasing the risk of tropical low and cyclone formation across the region.
Sea surface temperatures remain warmer than average in the western Pacific, much of the Maritime Continent, and around northern Australia, particularly in the Coral Sea. Warmer Australian waters, especially in the tropics, can result in greater evaporation, humidity, cloudiness, and rainfall.
Climate change continues to influence Australian and global climates. Australia's climate has warmed by around 1.47 °C in 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.
Next update expected by 3 January 2022
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