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

Following links open in new window

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.

For the week ending 9 April, sea surface temperatures (SSTs) in the central equatorial Pacific Ocean were close to average. Warm anomalies were present in the far western Pacific, around eastern Australia, and in the eastern Pacific. Anomalies in the far eastern Pacific reach more than +1 °C, and more than +2 °C in a small area on the equator adjacent to the South American coast.

Warm SST anomalies also persist across much of the Pacific south of the equator.

The NINO 3 and 3.4 regions both warmed during the past fortnight. The NINO3 SST anomaly for the week ending 9 April was +0.7 °C, NINO3.4 +0.3 °C and NINO4 −0.1 °C.

The tropical Pacific remains neutral with respect to the El Niño-Southern Oscillation (ENSO). However, there are signs that El Niño may develop in 2017, with the Bureau's ENSO Outlook status at El Niño WATCH. El Niño WATCH means there is around a 50% chance of El Niño developing in 2017, which is approximately twice the normal likelihood.

Sea surface temperatures in the tropical eastern Pacific Ocean have warmed, with the warmth progressively spreading westwards since the start of the year. Additionally, waters in the eastern Pacific subsurface have also warmed over the past few weeks. Waters near the South American coastline near Peru remain warmer than average, which has contributed towards heavy rains and flooding in parts of South America.

The pattern of very warm ocean conditions in the far eastern Pacific but neutral conditions overall is unusual. International climate models suggest the steady warming of the tropical Pacific Ocean is likely to continue in the coming months. Seven of eight models indicate that sea surface temperatures will exceed El Niño thresholds during the second half of 2017. However, some caution should be exercised as models have lower accuracy at this time of year, and there remains a significant spread in possible forecast outcomes.

El Niño is often, but not always, associated with below average winter–spring rainfall over eastern Australia and warmer than average winter–spring maximum temperatures over the southern half of Australia. For example, of the 27 El Niño events since 1900, 18 have resulted in widespread dry conditions for Australia.

The Indian Ocean Dipole (IOD) has little influence on Australia from December to April. Current outlooks suggest the IOD is likely to remain neutral at least through to the end of winter.

Cloudiness remains below average near the Date Line. Cloudiness has been generally below average since the start of August 2016.

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

Trade winds for the 5 days ending 9 April were slightly stronger than average over the western tropical Pacific, and near average over the eastern half of the Pacific. Trade winds have been stronger than average over the western tropical Pacific for around one month.

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.

Climate models surveyed by the Bureau indicate that the central Pacific will continue to warm. All eight of the surveyed models indicate El Niño is likely to form. One model suggests El Niño may stall, only consolidating later in spring or summer, but the others indicate El Niño thresholds will be reached during winter 2017.

However, it should be noted that model outlooks that span the southern autumn period tend to have lower accuracy than outlooks issued at other times of the year. This means outlooks beyond May should be used with some caution.

SST anomalies for March show sea surface temperatures in the equatorial Pacific Ocean were close to average. Warm anomalies were present in the far eastern Pacific, across much of the Pacific south of the equator, and in the far western Pacific around eastern Australia and much of the Maritime Continent.

The March values for the NINO3, NINO3.4 and NINO4 regions were +0.5 °C, +0.2 °C and 0.0 °C, respectively.

The 30-day Southern Oscillation Index (SOI) to 9 April was +3.8 (90-day value −1.0). SOI values have generally been within the neutral range since mid-October.

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) is neutral. The weekly index value to 9 April was +0.32 °C.

The influence of the IOD on Australian climate is weak during December to April. This is due to the monsoon trough shifting south over the tropical Indian Ocean and changing the overall wind circulation, which in turn prevents an IOD ocean temperature pattern from being able to form. The monsoon trough remains strong in the southern hemisphere at present.

Current outlooks suggest a neutral IOD for the end of autumn, with some models indicating a positive IOD may form later in winter.

The four-month sequence of sub-surface temperature anomalies (to March) shows the sub-surface of the central to eastern equatorial Pacific Ocean was cooler than average during March. These cool anomalies were similar in strength to those observed for February.

Areas of weak warm anomalies were present in the top 150 m of the tropical Pacific west of 160°E.

The sub-surface temperature map for the 5 days ending 9 April shows temperatures were generally close to average across the sub-surface of the equatorial Pacific Ocean, although small areas of weak warm anomalies were present in the far western Pacific subsurface, and of weak cool anomalies in the east.

Product code: IDCKGEWW00