Australia’s Bureau of Meteorology believes it is now likely (estimated at a greater than 70% chance) that an El Niño will develop during the southern hemisphere winter. “Although the El Niño–Southern Oscillation (ENSO) is currently neutral, surface and sub-surface ocean temperatures have warmed considerably in recent weeks, consistent with a state of rapid transition” the Bureau reported this week. “International climate models surveyed by the Bureau indicate continued warming of the central Pacific Ocean in coming months. Most models predict sea surface temperatures will reach El Niño thresholds during the coming winter season.”
The ENSO Wrap-Up of the current state of the Pacific and Indian Ocean says:
El Niño is often, but not always, associated with below normal rainfall across large parts of southern and inland eastern Australia during the second half of the year. The strength of an El Niño does not always indicate how much it will influence Australian rainfall. Historically there are examples where weak events have resulted in widespread drought across large parts of Australia, while at other times strong events have resulted in relatively modest impacts. It is too early to determine the strength of this potential El Niño. Daytime temperatures tend to be above normal over southern Australia during El Niño.
The BOM report says the Indian Ocean Dipole (IOD) is currently in a neutral state. Model outlooks indicate the IOD will remain neutral through late autumn and early winter. The chance of a positive IOD event occurring will increase if an El Niño develops. Positive IOD events are typically associated with lower than normal winter and spring rainfall over parts of southern and central Australia.
At a world wide level El Ninos are associated with globally warm years.