BOM: 2015-16 El Niño has peaked

BOM: 2015-16 El Niño has peaked

Australian Bureau of Meteorology (BOM) reports that a number of El Niño-Southern Oscillation (ENSO) indicators suggest the 2015-16 El Niño has peaked in recent weeks.

"Tropical Pacific Ocean temperatures suggest this event is one of the top three strongest El Niño events of the past 50 years," the Bureau says. Additionally, climate models suggest the 2015-16 El Niño will decline during the coming months, with a return to ENSO neutral likely during the second quarter of 2016.

In the central to eastern tropical Pacific Ocean, the sea surface and sub-surface have cooled in recent weeks, though temperatures remain at strong El Niño levels.

Monthly sea surface temperatures in the tropical Pacific. Image credit: BOM

Index October November Temperature change
NINO3 +2.4 +2.4 no change
NINO3.4 +2.4 +2.3 0.1 °C cooler
NINO4 +1.7 +1.6 0.1 °C cooler

Baseline period 1961–1990.

In the atmosphere, the Southern Oscillation Index has eased to weak El Niño values. Recent bursts of westerly winds over the equatorial western Pacific may temporarily slow the decline of El Niño.

Based on the 26 El Niño events since 1900, around 50% have been followed by a neutral year, while 40% have been followed by La Niña.

All of the eight international climate models surveyed by the Bureau indicate that the current El Niño will show a steady decline from early 2016. Models also suggest neutral and La Niña are equally likely for the second half of 2016, with a repeat El Niño the least likely outcome.

Video courtesy NCAR/CISL

Indian Ocean sea surface temperatures remain very much warmer than average across the majority of the basin.

Featured image: NCAR / CISL

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