El Niño ends as tropical Pacific Ocean returns to neutral and climate models suggest La Niña is likely to form during the June–August period, according to the Australian Bureau of Meteorology
Climate models are forecasting the emergence of a La Niña Pacific Ocean cooling event over the next three months or so, according to the Australian Bureau of Meteorology (BoM).
Sea surface temperatures across the tropical Pacific have cooled over the past fortnight, supported by much cooler-than-average waters beneath the surface.
The powerful El Niño Pacific Ocean warming event the has driven up global surface temperatures over the last few months is ending and the tropical Pacific Ocean has returned to a neutral El Niño–Southern Oscillation (ENSO) state, according to the latest report from BoM.
In the atmosphere, indicators such as the trade winds, cloudiness near the Date Line, and the Southern Oscillation Index have also returned to so called ENSO neutral levels.
International climate models indicate the tropical Pacific Ocean will continue to cool, with six of the eight models surveyed by BoM suggesting La Niña is likely to form during the austral winter (June–August). However, individual model outlooks show a large spread between neutral and La Niña scenarios.
Changes in global atmospheric circulation patterns accompany La Niña and are responsible for weather extremes in various parts of the world that are typically opposite to those associated with El Niño, according to US space agency NASA. These patterns result from the colder than normal ocean temperatures inhibiting the formation of rain-producing clouds over the eastern equatorial Pacific region while enhancing rainfall over the western equatorial Pacific region (Indonesia, Malaysia and northern Australia.)
These patterns also affect the position and intensity (weakening) of jet streams and the behavior of storms outside of the tropics in both the Northern and Southern hemispheres.