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

Indian Ocean Dipole outlooks

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

Sea surface temperatures (SSTs) for the week ending 10 November remain warmer than average across much of the equatorial Pacific Ocean, and slightly cooler than average in parts of the east. Overall, patterns are consistent with a neutral ENSO state.

Warm anomalies in the western tropical Pacific have decreased compared to two weeks ago, while the strength of cool anomalies close to South America have also decreased, but have spread over a larger area. Weak cool anomalies have also decreased in strength to the north of Australia, but remain in the Coral Sea, and on the southern side of the Indonesian archipelago. SSTs are mostly within 2 degrees of average in areas close to Sumatra, with anomalies weakening slightly compared to two weeks ago; this weakening is tied in with the decrease in positive IOD index values. Warm anomalies also persist off the Horn of Africa, and remain similar to two weeks ago, reaching between 1 and 2 degrees warmer than average.

The latest values of the three key NINO indices in the tropical Pacific for the week ending 10 November are: NINO3 +0.5 °C, NINO3.4 +0.6 °C and NINO4 +0.8 °C. NINO3 has warmed slightly compared to two weeks ago, while the other two NINO regions have cooled.

Persistent NINO3 or NINO3.4 values warmer than +0.8 °C are typical of El Niño, while persistent values cooler than −0.8 °C typically indicate La Niña.

The tropical Pacific Ocean remains neutral with respect to the El Niño–Southern Oscillation (ENSO), while the strong positive Indian Ocean Dipole (IOD) continues.

Despite some weakening over the past fortnight due to a transient Madden–Julian Oscillation (MJO) event, IOD values remain strongly positive. Significantly warmer than average waters remain near the Horn of Africa, and cooler than average waters persist in the eastern Indian Ocean, south of Indonesia.

International climate models surveyed by the Bureau indicate the positive IOD is so strong that it is likely to be slow to decline and could persist into mid-summer.

Typically, a positive IOD brings below average spring rainfall to southern and central Australia with warmer days for the southern two-thirds of the country. Positive IOD events are often associated with a more severe fire season for southeast Australia.

In the tropical Pacific Ocean, the El Niño–Southern Oscillation (ENSO) remains neutral. While surface waters of the tropical Pacific Ocean are slightly warmer than average, atmospheric indicators are generally neutral.

Most climate models forecast ENSO-neutral conditions for the rest of 2019 and into the first quarter of 2020. When ENSO is neutral, it has little effect on Australian and global climate, meaning other influences are more likely to dominate. 

Cloudiness near the Date Line has fluctuated around average values since late April, consistent with neutral ENSO. However, cloudiness near the Date Line has generally remained below average since early to mid-September.

Equatorial cloudiness near the Date Line typically increases during El Niño (negative OLR anomalies) and decreases during La Niña (positive OLR anomalies).

Cloudiness in the eastern tropical Indian Ocean has been well below average, while cloudiness is well above average in the western Indian Ocean. This indicates a mature and strong positive Indian Ocean Dipole.

Trade winds for the 5 days ending 10 November were close to average across the tropical Pacific.

During El Niño there is a sustained weakening, or even reversal, of the trade winds across much of the tropical Pacific. Conversely, during La Niña, there is a sustained strengthening of the trade winds.

In the Indian Ocean, trade winds have generally been much stronger than average over the past few months, typical of a strong positive IOD phase. However, the most recent week has seen a weakening of the easterly trade winds, which coincided with the passage of the Madden–Julian Oscillation through the region. This weakening is likely to be temporary, with forecasts indicating a return of stronger easterly trade winds.

All eight surveyed international climate models indicate central tropical Pacific sea surface temperatures in the NINO3.4 region will remain at ENSO-neutral levels into early 2020.

One model indicates that values may move towards La Niña thresholds over autumn, surpassing the threshold value during April. The remaining models all maintain NINO3.4 values within the neutral range throughout the outlook period.

Sea surface temperatures (SSTs) for October were warmer than average across much of the equatorial Pacific Ocean, and cooler than average in some parts of the eastern tropical Pacific close to South America.

SSTs were warmer than average in areas around southeastern Australia and much of western Australia. SSTs were mostly close to average around the rest of Australia, though there were cool anomalies in some areas to the north of Australia.

The October values for NINO3 were +0.3 °C, NINO3.4 +0.6 °C, and NINO4 +1.0 °C. All three NINO indices warmed compared to September.

The 30-day Southern Oscillation Index (SOI) for the 30 days ending 10 November was −5.7. The 90-day value was −9.1. The 30-day SOI values have remained fairly similar and within the ENSO-neutral range for about three and a half weeks.

Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.

The Indian Ocean Dipole (IOD) remains strongly positive, although IOD index values have decreased compared to values observed in recent weeks. The latest weekly value to 10 November was +1.67 °C.

The strong temperature gradient persists across the Indian Ocean. SSTs to the south of the Indonesian islands of Sumatra are up to 2 degrees cooler than average for the week ending 10 November, while warm anomalies in the west of the Indian Ocean near the Horn of Africa are up to 2 degrees warmer than average. The overall pattern of sea surface temperatures has remained generally consistent with a positive IOD pattern since late May. A positive IOD often results in below average winter–spring rainfall over southern and central Australia. It also typically means warmer than average winter–spring days for the southern two-thirds of Australia.

All six international climate models surveyed by the Bureau indicate the IOD will remain positive into December, with five of the six models indicating persistence into January.

While the IOD continues to show signs it will persisted later than usual this year, it remains unlikely that the positive IOD will persist into the second half of summer. IOD events dissipate as the monsoon trough moves into the southern hemisphere, which changes the broadscale wind patterns over the IOD region and returns sea surface temperatures to near average.

The four-month sequence of equatorial sub-surface temperature anomalies (to October) shows cool anomalies in the western equatorial Pacific, at a depth of around 100 to 200 m, and in the shallow sub-surface east of 110°W between 50 to 100 m depth. Weak warm anomalies extend across most of the top 200 m in most of the remainder of the equatorial Pacific.

Warm anomalies in the central Pacific have intensified in October, compared to September and August, while cool anomalies in the east and west have weakened. Warm anomalies reach up to 2.5 degrees warmer than average in small regions.

For the five days ending 11 November water temperatures were close to average across much of the sub-surface of the equatorial Pacific, with areas of the top 100 m slightly warmer than average in both the west and east of the equatorial Pacific.

Product code: IDCKGEWW00