Climate Model Summary

Climate Model Summary Archive: June 2014

El Niño remains likely for 2014

The tropical Pacific Ocean remains on track for an El Niño to develop in 2014. Half of the climate models surveyed by the Bureau suggest El Niño will become established by September, with most of the climate models (BoM) indicating an El Niño will develop by the end of the southern hemisphere spring. This is a small reduction in the number of models to forecast El Niño to develop during the winter. Similarly, the strength of the sea surface temperature anomalies forecast by individual models has eased slightly, indicating the chance of some slowdown in current El Niño development.

El Niño is often, but not always, associated with below-average rainfall during the second half of the year across large parts of southern and inland eastern Australia. Daytime temperatures also tend to be above average over southern Australia.

The Indian Ocean Dipole (IOD) is also currently neutral. Model outlooks suggest the IOD is likely to remain neutral throughout the southern winter and spring.

NINO3.4 outlook

The latest NINO3.4 forecasts (initialised in June) indicate the tropical Pacific Ocean is likely to continue warming over the coming months. Most models indicate sea surface temperatures in the central tropical Pacific will be above or close to El Niño thresholds by September, with most near the threshold by November.

The range in forecast values of NINO3.4 is quite wide when considering individual ensemble members (forecast scenarios) from each model with values ranging between 0.0 °C and +3.0 °C by November. (See the 'Models' tab for links to individual model output for NINO3.4).

The most recent NINO3.4 value is +0.4 °C for the week ending 15 June 2014. Sustained NINO3.4 values above +0.8 °C indicate El Niño conditions.

Indian Ocean Dipole (IOD) outlook

The IOD index remains neutral with a latest weekly value of –0.1 °C for the week ending 8 June 2014. The chance of a positive IOD event is elevated during El Niño events which can exacerbate rainfall reductions resulting from the El Niño.

The following graph shows 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.

Predictive Ocean Atmosphere Model for Australia (POAMA)

POAMA, run at the Bureau of Meteorology, generates an eight-monthly forecast on the first day of each month. The most recent model run (started in June) predicts NINO3.4 is likely to just exceed El Niño thresholds around July and remain very close to the threshold throughout the forecast period. The following forecast values (at the top of the table) are for the ensemble mean.

POAMA archive data is available here.

ENSO Dials

The arrows on the dials below indicate the combined average ofmonthly NINO3.4 outlooks from a survey of international global climate models. Note that the individual model runs vary around the average.

ENSO dial month+1 ENSO dial month+3 ENSO dial month+5

NINO3.4 outlook bar-graphs

The following graphs shows 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.

NINO3.4 bar graph month+1 NINO3.4 bar graph month+3 NINO3.4 bar graph month+5

IOD outlook bar-graphs

The following graph shows 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.

IOD bar graph month+1 IOD bar graph month+3 IOD bar graph month+5

Past climate model summaries