Today’s update from Australia’s Bureau of Meteorology indicate the tropical Pacific Ocean is likely to continue warming over the coming months. Most models, reports the Bureau, indicate sea surface temperatures in the central tropical Pacific will be above or close to El Niño thresholds by August, with all but one exceeding the threshold by October. Four models show NINO3.4 values considerably higher than the El Niño threshold by the end of the forecast period.
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 October. (See the ‘Models’ tab for links to individual model output for NINO3.4).
The most recent NINO3.4 value is +0.5 °C for the week ending 11 May 2014. Sustained NINO3.4 values above +0.8 °C indicate El Niño conditions.
The following graph 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.
The BOM does note that several of the surveyed climate models have eased their predictions slightly since the last update but around half continue to indicate that the equatorial Pacific is likely to exceed El Niño thresholds before or during the southern hemisphere spring. An El Niño ALERT remains in place, indicating at least a 70% chance of an El Niño developing in 2014.