Climate Model Summary

Climate Model Summary Archive: July 2013

ENSO remains neutral; negative IOD likely

The tropical Pacific remains neutral with respect to the El Niño-Southern Oscillation (ENSO). While the Bureau of Meteorology's model favours weak La Niña conditions throughout the rest of winter, other international models indicate ENSO neutral conditions will continue through to the end of the year.

In the tropical Indian Ocean, the Indian Ocean Dipole (IOD) is currently in a negative phase. All international models surveyed by the Bureau of Meteorology suggest this negative event is likely to persist throughout the southern winter and into spring. A negative IOD event during winter-spring increases the chances of above normal rainfall over southern Australia.

NINO3.4 Outlook

The NINO3.4 consensus outlook indicates neutral ENSO conditions (neither El Niño nor La Niña) are likely to persist. While the latest forecasts (initialised in July) from the surveyed international models indicate ENSO neutral conditions, the Bureau's model (POAMA) favours a weak La Niña event to develop during the winter months. The most recent NINO3.4 value is -0.1°C for the week ending 17 July 2013.

Indian Ocean Dipole (IOD)

The IOD index is currently negative, with a value of -0.7°C for the week ending 14 July 2013. The IOD consensus outlook indicates that this negative event will continue throughout winter and into spring with all but one of the international models predicting values to still be exceeding the negative IOD threshold in October.

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 July) predicts NINO3.4 is likely to cool by the end of winter into early spring, dropping just below La Niña thresholds. Neutral values are forecast to return later in the year. The following forecast values 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