Neutral conditions (neither El Niño nor La Niña) continue in the tropical Pacific. Model forecasts and expert opinion suggest that neutral conditions are likely to be maintained through the boreal summer and autumn of 2013, though a slight chance of La Niña or ElNiño development remains. National Meteorological and Hydrological Services and other agencies will continue to monitor the conditions over the Pacific and provide outlooks to assess the most likely state of the climate through the remainder of 2013.
During the last year, El Niño-Southern Oscillation (ENSO) indicators in the tropical Pacific (e.g., tropical Pacific Ocean temperatures, sea level pressure, cloudiness and trade winds) have generally been at neutral levels, indicating that neither El Niño nor La Niña conditions have been present. In January and February 2013, sea surface temperatures approached a borderline LaNiña level, and although the atmospheric characteristics of La Niña also appeared briefly, the ocean-atmosphere system as a whole did not remain in a La Niña state for long enough to be considered a weak La Niña event. Since March 2013 the central tropical Pacific Ocean, cloudiness and trade winds have been at neutral levels. However, in the far eastern tropical Pacific Ocean temperatures cooled to well below average during May and early June.
The latest outlooks from climate models and expert opinion suggest that sea surface temperatures and atmospheric anomalies are most likely to remain neutral through the end of 2013. Less than a quarter of the models surveyed predict weak La Niña conditions to develop during the June to September period, while less than one fifth of the models predict El Niño development during 2013. Hence, while there is a slight possibility for La Niña or El Niño development during the coming few months, neutral ENSO conditions are considered most likely during boreal summer and through the remainder of 2013.>> Update