El Nino WATCH cancelled; ENSO neutral likely for 2017

20/06/2017

The Bureau's ENSO Outlook has been downgraded from El Niño WATCH to INACTIVE.

This follows a reversal of the early autumn warming in the eastern tropical Pacific Ocean, and an easing of climate model outlooks. The tropical Pacific Ocean is likely to remain neutral with respect to the El Niño–Southern Oscillation in 2017.

In the atmosphere, the trade winds and Southern Oscillation Index are well within the neutral range. Equatorial sea surface temperatures in the central Pacific are slightly warmer than average.

However, far eastern Pacific Ocean sea surface temperatures, which were several degrees above normal near the Peruvian coast during March and April, cooled during May and June.

This warmth had the potential to spread and develop into an El Niño event with global effects, but eased as trade winds failed to reinforce the ocean warmth. Other ENSO indicators also remain neutral. All eight international models surveyed by the Bureau now suggest tropical Pacific Ocean temperatures are likely to remain ENSO-neutral for the second half of 2017.

This compares to seven of eight models that suggested a possible El Niño in April. While models have steadily eased back the likelihood of El Niño, most still indicate an increased chance of warmer and drier than average conditions for Australia over winter.

The Indian Ocean Dipole (IOD) is neutral. Three out of six climate models suggest a positive IOD will develop by the end of winter, and three are neutral. A positive IOD is typically associated with a drier than average winter and spring for southern and central Australia.