The El Niño/Southern Oscillation has a major influence on climate patterns in various parts of the world. This naturally occurring phenomenon involves fluctuating ocean temperatures in the central and eastern equatorial Pacific, coupled with changes in the atmosphere. Scientific progress on the understanding and modelling of this phenomenon has improved prediction skills to within a range of one to nine months in advance, giving society the opportunity to prepare for associated hazards such as heavy rains, floods and drought.
September 2018
Sea surface temperatures in the east-central tropical Pacific as well as most of the overlying atmospheric indicators show that ENSO-neutral conditions (neither El Niño nor La Niña) continue to prevail. However, most dynamical and statistical forecast models suggest an imminent warming of the tropical Pacific, reaching a weak El Niño level by the fourth quarter of the year. The chance of El Niño is about 70%, with uncertain strength, as model predictions range from ENSO-neutral to a moderate strength El Niño. National Meteorological and Hydrological Services will continue to closely monitor changes in the state of ENSO over the coming months.
In summary:
Conditions in the ocean and atmosphere in the tropical Pacific have remained neutral since April 2018
Model predictions and expert opinion indicate that El Niño/Southern Oscillation conditions are about 70% likely to reach weak El Niño levels by the fourth quarter of 2018 and into the Northern Hemisphere winter 2018-2019
While predictions of El Niño and La Niña have relatively high confidence at this time of the year, some uncertainty is reflected by the broad range of model forecasts currently available, which generally indicate the sea surface temperatures to be 0.6 to 1.2°Celsius above average in the east-central topical Pacific during the period of November 2018 through January 2019. A strong El Niño event appears unlikely.
Through Northern Hemisphere winter 2018-19, the development of La Niña can be practically ruled out.
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