Climate Model Summary

Climate Model Summary Archive: May 2013

Neutral ENSO, possible negative IOD development

The tropical Pacific remains in a neutral El Niño-Southern Oscillation (ENSO) state. All atmospheric and oceanic indicators of ENSO are currently within neutral values. All international models surveyed by the Bureau of Meteorology suggest that neutral ENSO conditions are likely to continue through the winter months and into spring.

Four of the five international models surveyed are suggesting the development of a negative Indian Ocean Dipole (IOD) event in late winter. A negative IOD event during winter-spring increases the chances of above normal rainfall over southern Australia.

NINO3.4 Outlook

The NINO3.4 outlook indicates neutral ENSO conditions (neither El Niño nor La Niña) are likely to persist. The latest forecasts (initialised in May) from the surveyed international models predict the index will remain neutral throughout the austral winter and into spring. The most recent NINO3.4 value is +0.1°C for the week ending 12 May 2013.

Indian Ocean Dipole (IOD)

The IOD index is currently neutral, with a value of 0.0°C for the week ending 12 May 2013. The IOD consensus outlook indicates that there is an increased chance of a negative IOD event developing by the end of the austral winter with four out of five models reaching the negative IOD thresholds by August.

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 May) predicts NINO3.4 is likely to remain neutral throughout the winter and spring months. 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