MELBOURNE, Australia – The El Niño–Southern Oscillation (ENSO) remains neutral, and the positive Indian Ocean Dipole (IOD) event continues but has weakened, according to the Australian Government Bureau of Meteorology (BOM). IOD values have gradually weakened since their peak of +2.1 °C in mid-October. However, the latest weekly value of +0.9 °C is still well above the positive IOD threshold value of +0.4 °C.
Warmer than average waters persist near the Horn of Africa, but the cooler than average waters in the eastern Indian Ocean have now returned to near-average sea surface temperatures. Trade winds remain stronger than average over the tropical Indian Ocean.
Most international climate models surveyed by the Bureau indicate the positive IOD will dissipate by mid-summer as the monsoon moves into the southern hemisphere.
Typically, a positive IOD brings below average rainfall to southern and central Australia with warmer days for the southern two-thirds of the country.
Positive IOD events are often associated with a more severe fire season for southeast Australia. Recent flooding in eastern Africa is also typical of a positive IOD event.
In the tropical Pacific Ocean, the El Niño–Southern Oscillation (ENSO) remains neutral.
However abnormally warm sea surface temperatures in the western tropical Pacific may be contributing to some changes in weather patterns over the region.
International climate models forecast ENSO-neutral for early 2020. When ENSO is neutral, it has a reduced effect on Australian and global climate, and other influences are more likely to dominate.