1. Current State of the Pacific and Indian Oceans
Climate Information Services
Australian Bureau of Meteorology
Yuriy Kuleshov

4. ENSO Wrap-Up

5. Monthly SST anomalies
Sea surface temperature (SST) anomalies for August show SSTs were close to average along the equator in the Pacific Ocean. Warm anomalies were located across most of the south Pacific with the strongest anomalies occurring off the east Australian coastline and to the east of New Zealand. Large parts of the North Pacific between Indonesia and Japan also had SSTs of more than 1 °C warmer than average.
The August values for the NINO3.4, NINO3 and NINO4 regions were 0.0 °C, 0.0 °C and +0.4 °C, respectively. All three August values cooled with respect to July, but remain firmly within the neutral range.
Index
July
August
Temperature change
NINO3
+ 0.3 °C
0.0 °C
0.3 °C cooler
NINO3.4
+ 0.4 °C
0.4 °C cooler
NINO4
+ 0.5 °C
0.1 °C cooler
Baseline period

6. Monthly sub-surface temperatures
The four-month sequence of sub-surface temperature anomalies (to August) shows cool anomalies developing in the central to eastern equatorial Pacific Ocean down to a depth of 150 m. In some areas these anomalies are up to 3.0°C cooler than average for the month of August. Weak warm anomalies persist in the shallow sub-surface waters of the western equatorial Pacific Ocean.

7. Southern Oscillation Index
The 30-day Southern Oscillation Index (SOI) to 10 September is +6.8 (90-day value +3.3), within the ENSO neutral range.
Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between about +7 and −7 generally indicate neutral conditions.

8. 5-day SST and wind anomalies
Trade winds for the 5 days ending 10 September were slightly stronger than average over the western tropical Pacific and near average in the central and eastern tropical Pacific. These stronger trades may be assisting the cooling of sea surface temperatures.
During La Niña events, there is a sustained strengthening of the trade winds across much of the tropical Pacific, while during El Niño events there is a sustained weakening, or even reversal, of the trade winds

9. POAMA long-range outlook
Agency/Source/Provider
Model
BOM - Bureau of Meteorology
POAMA
Meteorological Service of Canada
CanSIPS
ECMWF (EU)
System4
JMA
JMA/MRI-CGCM
METEO-FRANCE
ARPEGE
NASA - GMAO (USA)
GEOS5
NOAA - NCEP (USA)
CFSv2
UKMO
GloSea5
These model forecasts of the El Niño – Southern Oscillation (ENSO) are generated by the Predictive Ocean Atmosphere Model for Australia (POAMA), a dynamical computer model of the climate system run at the Bureau of Meteorology. 
The Bureau surveys eight international climate models to examine forecasts for the Pacific and Indian Oceans.

10. NINO3.4 - climate model summary October 2017 to February 2018
The latest outlooks suggest that the central tropical Pacific Ocean will continue to cool in the coming months with four out of eight models suggesting La Niña thresholds may be met by December The other four models indicate that tropical Pacific waters will stay cooler than average, yet within the neutral range. If La Niña thresholds are reached it remains to be seen if levels would be sustained sufficiently long (around 3 months) to be considered an event. The most recent weekly NINO3.4 value (to 17 September) is −0.3 °C.
The Bureau routinely monitors oceanic and atmospheric conditions and model outlooks. NINO3.4 values that persist below −0.8 °C typically indicate La Niña, while persistent values above +0.8 °C typically indicate El Niño.

11. Indian Ocean Dipole
and
POAMA, run at the Bureau of Meteorology, generates a nine-month forecast each fortnight. The most recent model run (generated 10 September) indicates IOD will remain neutral throughout the forecast period.

12. IOD - climate model summary for October 2017 to February 2018
The IOD is currently neutral with the weekly IOD index value (to 17 September) at +0.1 °C. 
Three out of six models suggest that a positive IOD event could develop in spring and decay by early summer at the latest. The remaining models favour a neutral IOD for the rest of 2017. 

13. WMO GPC Melbourne climate outlook
WMO Global Producing Centre (GPC) for long-range forecasts, Melbourne, Australia
Developed as part of the ICCAI, Pacific Adaptation Strategy Assistance Program (PASAP)

14. September to November 2017 climate outlook - SSTs

15. September to November 2017 climate outlook – Accumulated Rainfall

16. September to November 2017 climate outlook – Accumulated Rainfall

17. October to December 2017 climate outlook – Accumulated Rainfall

18. Summary http://www.bom.gov.au/climate/enso/
Chances of a late season La Niña increase
The El Niño-Southern Oscillation (ENSO) is currently neutral.
However, all eight international climate models suggest that the tropical Pacific Ocean is likely to continue its current cooling trend in the coming months, with three models reaching La Niña thresholds during the austral spring and with a fourth reaching the threshold in early summer However, models suggest the cool Pacific temperatures may warm by late summer, which is typical of the ENSO cycle.   
The Indian Ocean Dipole (IOD) is currently neutral. Three out of six models indicate that a positive IOD event may develop in spring 2017, but decay by the end of summer. 

19. Further information - BoM
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