Climate Model Summary

Climate Model Summary Archive: April 2013

Neutral ENSO conditions expected to persist

The tropical Pacific remains in a neutral El Niño-Southern Oscillation (ENSO) state. Atmospheric and oceanic indicators of ENSO generally remain within neutral values, despite the Southern Oscillation Index (SOI) exhibiting some fluctuations over the past month (due to a localised effect from high pressure systems near Tahiti). For more details, please see the ENSO Wrap-Up.

All international models surveyed by the Bureau of Meteorology suggest that neutral ENSO conditions are likely to continue through the autumn and winter months, although predictions during the April to June period are known to be less skilful. Six of the seven models, expect NINO3.4 values to remain within the −0.4 to +0.4 °C range by early spring, solidly within the neutral range.

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 April) from the surveyed international models predict the index will remain neutral until at least the austral spring. The most recent NINO3.4 value is +0.1°C for the week ending 14 April 2013.

Indian Ocean Dipole (IOD)

The IOD index is currently neutral, with a value of 0.0°C for the week ending 14 April 2013. The IOD consensus outlook suggests neutral conditions may persist through to September. However, model outlooks increase the odds of a negative IOD event as time progresses, with 3 of the 5 models exceeding negative IOD thresholds by September.

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 April) predicts NINO3.4 is likely to remain neutral throughout autumn and winter. 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