25 MAY 2017
- The El Niño-Southern Oscillation (ENSO) remains neutral. However, the SPREP’s ENSO Outlook status is at El Niño WATCH, meaning there is around a 50% chance of El Niño developing in 2017. Five of eight international climate models indicate that sea surface temperatures (SSTs) will exceed El Niño thresholds during the second half of 2017. It should be noted that models have lower accuracy at this time of year.
- A weak Madden-Julian Oscillation (MJO) signal emerged over the western Pacific in the last two weeks, strengthening marginally as it moved eastward. Climate models indicate the MJO is likely to remain at moderate strength and progress slowly over the western hemisphere in the coming weeks. The development of tropical cyclone Donnato the north of Vanuatu and Ella over Samoa and Fiji; and recent enhanced South Pacific Convergence Zone (SPCZ) activity is likely to be associated with the MJO signal over the western Pacific Ocean.
- The Intertropical Convergence Zone (ITCZ) was suppressed in the far western Pacific and near the Date Line in April. In the southwest Pacific, the northern component of the SPCZ was enhanced both west and east of the Date Line. SPCZ activity was suppressed to the northwest of New Caledonia, over Fiji and Tonga.
- Seasonal rainfall outlooks for May to July 2017 favour below average rainfall for southern Vanuatu and western Fiji. Model outlooks vary elsewhere.
- The official 2016-17 southwest Pacific tropical cyclone season ended on 30 April 2017. Currently an out-of-season category 5 tropical cyclone named Donnais present to the north of Vanuatu and Ella over Samoa and Fiji. Five tropical cyclones have formed in the southwest Pacific since 1 November 2016.