Climate Model Summary

Models reduce Pacific warming, but still favour weak spring El Niño

The El Niño-Southern Oscillation (ENSO) remains neutral. Four of the eight models still favour an El Niño by August, with a fifth falling just short. Five of eight models predict El Niño in spring. With models now generally forecasting less warming and a weaker event than in recent months, the average NINO3.4 outlook falls short of El Niño levels in August, but reaches El Niño levels in October.

The Indian Ocean Dipole (IOD) is currently neutral. Outlooks suggest a positive IOD may develop during winter and persist into early spring. If a positive IOD were to occur in conjunction with El Niño, this can amplify any dry signal. However, it should be noted that model accuracy during autumn (for both ENSO and IOD outlooks) is lower than at other times of year.

NINO3.4 outlook

Six of the eight NINO3.4 model outlooks suggest that temperatures in the central tropical Pacific Ocean will continue to warm in the coming months. While all models have eased the amount of warming likely compared to outlooks issued since last month, five of the eight models still reach or exceed the El Niño threshold at some point during the outlook period.

The most recent weekly NINO3.4 value to 21 May is +0.5 °C. By August, the average of all the models is forecast to be +0.6 °C and by October, five of eight models exceed the El Niño threshold with the average value reaching +0.8 °C. It should be noted that this outlook starts during the autumn predictability barrier—typically the ENSO transition period—during which most models have their lowest outlook accuracy. Accuracy begins to improve from next month.

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.

Indian Ocean Dipole (IOD) outlook

The latest weekly IOD index value to 21 May is +0.3 °C, just touching the positive IOD threshold. Index values would have to be sustained at +0.4 °C or greater for at least eight weeks for this to be considered a positive IOD event.

Four of the six surveyed models suggest values are likely to remain greater than +0.4 °C, consistent with a positive IOD, during the southern winter and early spring. The remaining two models suggest the IOD will return to neutral values. However, model skill is low at this time of year, so caution should be exercised when using these forecasts.

A positive IOD is typically associated with below average winter-spring rainfall over southern and central Australia. When a positive IOD coincides with El Niño, dry conditions experienced across Australia during El Niño may be enhanced.

Predictive Ocean Atmosphere Model for Australia (POAMA)

POAMA, run at the Bureau of Meteorology, generates a nine-month forecast each fortnight. The most recent model run (generated 21 May) indicates NINO3.4 will start to cool during winter, but remain neutral throughout the forecast period. The POAMA forecast remains the coolest of the models surveyed, the result of different modelling processes and data fed into the model. The range of different model forecasts gives an indication of the possibilities for the months ahead. It should also be noted that this forecast is made during the autumn predictability barrier, meaning model skill is lower than at other times of the year.

The forecast values, shown below in bold, are for POAMA's ensemble mean.

Product code: IDCKGL0000

Australian climate is influenced by temperature patterns in the Pacific and Indian Oceans. This page provides information on Pacific and Indian Ocean outlooks for the coming six months based on a survey of international climate models.

Further details: ENSO Wrap-Up (ENSO and IOD); Climate Outlooks

Average of international model outlooks for NINO3.4

Average of international model outlooks for the Indian Ocean Dipole (IOD)

Based on the ensemble mean for the most recent model run.

The arrows on the dials indicate the combined average of monthly outlooks from a survey of international global climate models. Note that the individual model runs vary around the average.

More information:

NINO3.4 covers the central Pacific region.

Graphs

Nino 3.4 2 month outlook Models information
Graph details

The graphs are based on the ensemble mean for the most recent model run.

These graphs show the average forecast value of NINO3.4 for each international model surveyed for the selected calendar month. If the bars on the graph are approaching or exceeding the blue dashed line, there is an increased risk of La Niña. Similarly, if the bars on the graph are approaching or exceeding the red dashed line, there is an increased chance of El Niño.

Graphs

Latest POAMA IOD outlook Models information
Graph details

The graphs are based on the ensemble mean for the most recent model run.

Thse graphs show the average forecast value of the IOD index for each international model surveyed for the selected calendar month. If the majority of models are approaching or exceeding the blue dashed line, then there is an increased risk of a negative IOD event. If the majority of models are approaching or exceeding the red dashed line, then there is an increased risk of a positive IOD event.

POAMA Long-Range Outlook

Issued 21 May 2017

Updated fortnightly

These model forecasts of the El Niño – Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) 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. They are included in the monthly model summary of predictions from POAMA and other models operated by international organisations.

POAMA outlooks provide forecasts out to nine months ahead. The model ensemble distributions shown here provide a range of possible developments in sea surface temperature (SST) in the equatorial Pacific Ocean (NINO regions) and for the Indian Ocean.

NINO34 predictions for the next 9 months.

Skip to past graph to table of values

Outlook graph for selected indice

NINO34 probabilities

Click dates in the first row to see probability graphs
Outlook for month
NINO34 (°C) 0.17 -0.30 -0.45 -0.34 -0.24 -0.18 -0.14
Model cool frequency (<−0.8°C) 0% 3.03% 15.15% 6.06% 3.03% 0% 0%
Model neutral frequency 100% 96.96% 84.85% 93.94% 96.97% 100% 100%
Model warm frequency (>+0.8°C) 0% 0% 0% 0% 0% 0% 0%

Model details

The models used within our survey are listed below with links to their agency homepages, model output and technical information about the model.

Model data are provided for Bureau of Meteorology use by the agencies detailed in the Models section. Respective agency copyright applies to these data.