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 temperature (SST) anomalies are warmer than average across nearly the entire tropical Pacific Ocean. Compared to two weeks ago, surface waters have cooled in the east of the tropical Pacific.

SSTs are also warmer than average across much of the southern Pacific, particularly across areas south of 30°S, extending to waters around southeastern Australia and across the Great Australian Bight.

SSTs are also slightly warmer than average around northern Australia, from the Gulf of Carpentaria to waters to the northwest of Western Australia.

The latest values of the three key NINO indices in the tropical Pacific for the week ending 17 March are: NINO3 +0.6 °C, NINO3.4 +0.8 °C and NINO4 +0.8 °C. SSTs for the central (NINO3.4) and eastern (NINO3) regions have warmed compared to two weeks ago.

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 El Niño–Southern Oscillation (ENSO) is currently neutral. The Bureau's ENSO Outlook has moved to El Niño ALERT.

This means the chance of El Niño developing in 2019 has increased to approximately 70%, around triple the normal likelihood.

Tropical Pacific sea surface temperatures have touched on El Niño thresholds for the past three weeks, while waters below the surface are also slightly warmer than average. Signs of El Niño in the atmosphere are less clear. While values of the Southern Oscillation Index (SOI) are currently within El Niño bounds, the index is likely to weaken in the coming days. Large swings in the SOI are not uncommon during the southern hemisphere monsoon season. Additionally, trade winds have been closer to normal over the past fortnight after a period of weakened trades in the western tropical Pacific.

Most international climate models suggest sea surface temperatures in the central tropical Pacific Ocean are likely to remain at El Niño levels into winter. Sustained warmer than average ocean waters would increase the likelihood of coupling between the atmosphere and ocean, which would typically cause changes in Australian and global weather patterns. However, current outlooks have less skill for the period beyond May, and therefore predictions for the latter months should be viewed with some caution.

El Niño typically brings drier than average conditions for eastern Australia during winter–spring, and warmer days across southern Australia. During the autumn months, the influence of El Niño tends to be weaker, but can bring drier conditions to southern 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 for the remainder of the austral autumn, but indicate a positive IOD may form later in winter. A positive IOD typically means drier than average conditions for southern and central Australia during winter-spring.

Cloudiness near the Date Line has fluctuated over the past three months, but has tended to be above average since early December. Values during February were more strongly positive, associated with monsoon and tropical cyclone activity near the Date Line, and have been closer to average through March so far.

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

Trade winds for the 5 days ending 17 March were somewhat weaker than average across the western tropical Pacific.

This follows a period of more pronounced weakening of trade winds which had occurred during February, associated with the Madden-Julian Oscillation (MJO), and close to average trade wind strength in early March. The MJO is currently weak, and is not exerting a strong influence on trade winds at the moment.

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.

All but one of the eight surveyed climate models predict sea surface temperatures (SSTs) will remain above El Niño thresholds for April and June, with six of the models maintaining SSTs values above the threshold during August.

Most of the models indicate SSTs in the central tropical Pacific are likely to warm further as we move from autumn into winter.

It should be noted that model accuracy forecasting through the autumn months is lower than at other times of the year, due to the natural cycle of ENSO, and this may be contributing to the difference in outlooks across the models. Outlook skill improves for outlooks issued from May.

Sea surface temperatures (SSTs) for February were warmer than average along most of the equator in the Pacific Ocean, but close to average in the western tropical Pacific.

SSTs were warmer than average for a large part of the southern Pacific between about 170°E to 140°W in the mid-latitudes, and across most of the Pacific south of 30°S. Waters are also warmer than average across the Great Australian Bight, across the Tasman Sea, and to the east of New Zealand.

The February values for NINO3 were +0.5 °C, NINO3.4 +0.6 °C, and NINO4 +0.8 °C.

The 30-day Southern Oscillation Index (SOI) has been steady over the past two weeks, remaining within El Niño territory. The SOI value for the 30 days to 17 March was −13.3. However, the 90-day SOI is still well within neutral territory at −5.1.

While values of the 30-day SOI have been strongly negative for almost a month, SOI values during the northern Australian wet season can be volatile, and should therefore be viewed with caution. This is because the passage of tropical systems near Darwin and Tahiti can affect atmospheric pressure at these locations, and hence the value of the SOI.

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) has returned to neutral values during the past fortnight. The latest weekly index value to 17 March was −0.13 °C.

Despite the decline in IOD values, some temperature gradient remains across the Basin, with warmer than average SSTs across most of the Indian Ocean and near average temperatures across the north of the Basin.

Due to the movement of the monsoon trough in the Indian Ocean, the IOD typically has little influence on Australian climate from December to April. When the monsoon trough shifts southwards into the southern hemisphere, it changes the broadscale wind patterns, meaning that the IOD pattern is unable to form.

All of the six international climate models surveyed by the Bureau indicate that the IOD will be neutral for April. By June, two models indicate a positive IOD may form, with five models predicting positive IOD values during August.

A positive IOD during winter to spring often results in less rainfall than average over large parts of Australia.

The four-month sequence of sub-surface temperature anomalies (to February) shows warm anomalies across most of the top 200 m of the western to central equatorial Pacific sub-surface, and cool anomalies in the top 150 m sub-surface of the eastern equatorial Pacific.

Warm anomalies in the sub-surface have decayed over late 2018 and early 2019, although small parts of the sub-surface to the west of the Date Line remain more than two and a half degrees warmer than average.

Temperatures for the five days ending 17 March show warmer than average waters are present in an area of the central equatorial Pacific, around 100 m depth, and also in the top 100 m of the eastern equatorial Pacific. Warm anomalies in a small part of the central equatorial Pacific reach more than four degrees above average, although the volume of water this warm has decreased compared to two weeks ago.

Elsewhere temperatures are close to average.

Product code: IDCKGEWW00