Neutral conditions (neither El Niño nor La Niña) have continued in the tropical Pacific through recent months. Between July and September 2012, the tropical Pacific sea surface temperature increased to weak El Niño levels. However, because the overlying atmosphere failed to respond (i.e., sea level pressure, wind and cloud patterns were near normal), overall conditions remained neutral.
Model forecasts and expert opinion suggest that the likelihood of El Niño conditions developing during the remainder of 2012 is now low, and that neutral conditions are likely to persist into the first quarter of 2013. National Meteorological and Hydrological Services and other agencies will continue to monitor Pacific Basin conditions and provide outlooks to assess the most likely state of the climate through the last part of 2012 and into early 2013.
WMO has therefore issued a new Update to reflect the latest developments.
El Niño phenomenon is due to large-scale interactions between the ocean and the atmosphere. It is characterized by unusually warm ocean surface temperatures in the central and eastern tropical Pacific, in contrast to the unusually cool ocean surface temperatures witnessed in the same region during La Niña events. Both El Niño and La Niña have a large influence on weather and climate around the globe.