ENSO Wrap-Up
Current state of the Pacific and Indian oceans


Weekly sea surface temperatures

Graphs of the table values

Monthly sea surface temperatures

Graphs of the table values

5-day sub-surface temperatures

Monthly temperatures

Southern Oscillation Index

30-day SOI values for the past two years
Select to see full-size map of 30-day Southern Oscillation Index values for the past two years, updated daily.

Trade winds

5-day SST and wind anomaly from TAO/TRITON
Select to see full-size map of 5-day SST and wind anomaly from TAO/TRITON.

Cloudiness near the Date Line

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ENSO outlooks

NINO3.4 SST plumes from POAMA forecasts, updated daily
Select to see full-size map of NINIO3.4 SST plumes from POAMA forecasts, updated daily.

Indian Ocean Dipole outlooks

IOD SST plumes from POAMA forecasts, updated daily
Select to see full-size map of IOD SST plumes from POAMA forecasts, updated daily.

Sea surface temperatures (SSTs) in the tropical Pacific Ocean remain within neutral thresholds, but have warmed slightly over the past fortnight. This warming has been observed across all NINO indices. 

Western Pacific SSTs are warmer than average, with waters in the Maritime Continent and that surrounding Australia 1-2 °C warmer than average. However, compared to a few weeks ago, the warm anomalies surrounding Tasmania have eased slightly.

SSTs over large parts of the Indian Ocean remain more than 1 °C above average, but have largely cleared from the western Indian Ocean over the past four or five weeks.

 

The tropical Pacific Ocean remains in a neutral El Niño–Southern Oscillation (ENSO) state—neither El Niño nor La Niña—with all ocean and atmospheric indicators now near normal.

Recent observations and climate model forecasts continue to suggest La Niña may develop in the coming months, hence the Bureau’s ENSO Outlook remains at La Niña WATCH level. A La Niña WATCH means there is a 50% likelihood of La Niña developing during the second half of 2016.  If La Niña does develop, climate models suggest it is unlikely to reach levels seen in the most recent event of 2010–12, which was one of the strongest La Niña events on record.

La Niña is typically associated with higher than usual winter and spring rainfall over northern, central and eastern Australia, and cooler than normal daytime temperatures south of the tropics.

Warm ocean temperatures to the north of Australia, in the Indian Ocean, and in the Tasman Sea are also currently influencing Australia’s climate. Warm ocean temperatures surrounding Australia provide more moisture to weather systems that pass over the oceans and potentially change the path weather systems take, resulting in more systems reaching the continent.

Warm ocean temperatures to the northwest of Australia can be associated with a negative Indian Ocean Dipole (IOD), especially when they occur at the same time as cooler than usual ocean in the tropical western Indian Ocean, near the African coast.  Climate models and current observations suggest a negative IOD may be in the early stages of development. However several more weeks of similar ocean temperature patterns would need to be observed before 2016 is considered a negative IOD year. Negative IOD events typically bring higher than usual winter and spring rainfall to southern Australia.

Cloudiness near the Date Line has been close to average since the beginning of May.

Equatorial cloudiness near the Date Line typically increases during El Niño (below average OLR) and decreases during La Niña (above average OLR).

Trade winds near the equator in the Pacific Ocean have remained close to normal for the 5 days ending 19 June.

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.

International models have weakened their outlook for La Niña compared to last month. While all models still indicate more cooling in the tropical Pacific Ocean is likely, only four of eight models now suggest La Niña could form in the second half of 2016. The other four models remain neutral. If La Niña does form, models do not suggest it will be as strong as the near-record event of 2010-12.

May 2016 SSTs remained more than 1 °C above average over parts of the tropical eastern and central Pacific away from the equator. Along the equator in the eastern and central Pacific, cool anomalies covered the largest area since February 2014. The decrease in SSTs in the tropical central and eastern Pacific was consistent with the decay of El Niño.

SSTs northeast of Australia have increased since April and are again more than 1 °C warmer than average in parts.

May NINO values showed that the NINO3 region in the eastern Pacific cooled by 0.6 °C compared with April, after a similar drop the previous month. The NINO3.4 region also cooled by 0.6 °C compared to April, accelerating its cooling trend since the end of 2015. Drops of this magnitude are rarely seen and indicate the 2015-16 El Nino has declined at a rapid pace. Values in the Bureau dataset for NINO3, NINO3.4 and NINO4 were +0.2 °C, +0.4 °C and +0.6 °C for May, respectively.

Warmer than average SSTs in the western Indian Ocean returned to near average temperatures during May. SSTs in the eastern Indian Ocean also cooled but remain more than 1 °C warmer than average in parts.

The 30-day Southern Oscillation Index (SOI) to 19 June 2016 is +3.7; within the neutral ENSO range. This is the highest 30-day SOI value since June 2014.

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.

The Indian Ocean Dipole (IOD) index has been below -0.4 °C for the past four weeks, with a latest weekly value of -0.6 °C for the week ending 19 June 2016. To be considered a negative IOD event, it would take several more weeks of IOD index values below the threshold value. International climate models suggest these negative values are likely to persist over the coming months, with all models suggesting a negative IOD event will develop in the winter-spring months.

Negative IOD events are more likely to occur during La Niña. Typically a negative IOD brings above average winter-spring rainfall to southern Australia.

More broadly, sea surface temperatures (SSTs) are significantly warmer than average across much of the Indian Ocean. This warmth will likely provide more available moisture to weather systems as they cross the Australian continent.

The four-month sequence of sub-surface temperature anomalies shows a clear cooling trend in the top 100 m of the equatorial Pacific since February. Cool anomalies have spanned the entire equatorial Pacific since April, and May removed almost all remaining warmer than average water from the top 50 m. The top 50 m of water west of 150° W is mostly close to average temperature; east of 150° W the water is cooler than average.

Waters remain generally cooler than average beneath the surface of the equatorial Pacific. Temperatures in the top 50 m remain close to average, while 100-200 m below the suface, waters are more than 4 °C cooler than average in parts.

Product code: IDCKGEWW00