Current State of the Pacific and Indian Oceans Climate Information Services Australian Bureau of Meteorology Yuriy Kuleshov http://www.bom.gov.au/climate/enso/

ENSO Wrap-Up http://www.bom.gov.au/climate/enso/

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 http://www.bom.gov.au/climate/enso/#tabs=Sea-surface Baseline period 1961-1990

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. http://www.bom.gov.au/climate/enso/#tabs=Sea-sub%E2%80%93surface

Southern Oscillation Index http://www.bom.gov.au/climate/enso/#tabs=SOI 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.

5-day SST and wind anomalies http://www.bom.gov.au/climate/enso/#tabs=Trade-winds 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

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 http://www.bom.gov.au/climate/enso/#tabs=Outlooks 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.

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 2017. 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. http://www.bom.gov.au/climate/model-summary/#tabs=Pacific-Ocean

Indian Ocean Dipole http://www.bom.gov.au/climate/enso/#tabs=Indian-Ocean and http://www.bom.gov.au/climate/poama2.4/poama.shtml 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.

IOD - climate model summary for October 2017 to February 2018 http://www.bom.gov.au/climate/model-summary/#tabs=Indian-Ocean 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. 

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) http://poama.bom.gov.au/experimental/pasap/ http://poama.bom.gov.au/experimental/pasap/

September to November 2017 climate outlook - SSTs http://poama.bom.gov.au/experimental/pasap/

September to November 2017 climate outlook – Accumulated Rainfall http://poama.bom.gov.au/experimental/pasap/

September to November 2017 climate outlook – Accumulated Rainfall http://poama.bom.gov.au/experimental/pasap/

October to December 2017 climate outlook – Accumulated Rainfall http://poama.bom.gov.au/experimental/pasap/

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 2017-18. 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.  http://www.bom.gov.au/climate/enso/

Further information - BoM Climate information: www.bom.gov.au/climate Stay up-to-date on El Niño: www.bom.gov.au/climate/enso/ Subscribe to e-news: www.bom.is/enviro-news