12-Month Rainfall Forecast

Issue Notes

ENSO status: La Niña. IOD status: Neutral, returned from negative phase this month. SAM status: Positive, it is forecast to be mostly positive until at least December. The El Niño–Southern Oscillation (ENSO) is currently neutral. However, Over the past few months, sea surface temperatures in the central and eastern equatorial Pacific Ocean have continued to cool. This oceanic cooling has also been accompanied by a response in the atmosphere, which has included trade winds strengthening over the central and western Pacific Ocean in the last few weeks. Both the atmosphere and the ocean are now showing clear signs of La Niña pattern and all forecast models suggest that this trend will continue during December and January. Four of seven models continue the event until February and only one through until March. La Niña typically brings above average rainfall to much of Australia, particularly the north and east. The Indian Ocean Dipole (IOD) is currently neutral, it returned from a negative phasein winter and early spring. While the IOD has returned to neutral, the abnormally warm oceans to the northwest of Australia, will take a month or two to cool, bringing cooler daytime temperatures to southern Australia for another month or so. As such, average to above average rainfall is predicted across much of the country for the remainder of spring and summer. Heavy rainfall events are also more likely during La Niña years, due the abundant moisture it feeds into Australia.