Island Climate Update

A monthly summary of the climate in the tropical South Pacific islands, with an outlook for the coming months. This bulletin is a multi-national project with collaboration from a number of Pacific nations and support from various organisations.

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Issues

During July 2019, SSTs dipped below El Niño thresholds in the central Pacific for the first time in 5 months.
During June 2019, the atmosphere continued to respond to a warm pool of water in the central and western Pacific, with above normal rainfall and cloud centred along and just west of the International Dateline.
During May 2019, the atmosphere continued to respond to a warm pool of water in the central and western Pacific,
During April 2019, the atmosphere once again responded to a warm pool of water in the central and western Pacific, withabove normal rainfall and cloud centred along and just west of the International Dateline
Warmer than average sea surface temperatures (SSTs) now cover the tropical Pacific uniformly, a sign of a strengthening oceanic El Niño event.
Over the past month, Sea surface temperatures (SSTs) remained above average in the equatorial Pacific Ocean, particularly near and just west of the International Dateline. The NINO3.4 index SST anomalies however remained just below +0.5 ̊C during February 2019.
Over the past month, sea surface temperatures (SSTs) in the central Pacific have remained above normal particularly near and west of the International Dateline, although declined slightly below the conventional threshold for El Niño.
Over the past month, sea surface temperatures (SSTs) in the central Pacific have remained above normal with the NINO3.4 index anomalies currently exceeding +0.8°C
Sea surface temperatures (SSTs) across the east-central tropical Pacific have reached weak El Niño conditions.
Sea surface temperatures (SSTs) in the central Pacific (NINO3.4 Index) warmed notably over the past month, increasing from an anomaly of +0.25°C in September to +0.75°C in October.
For the sixth consecutive month, ENSO-neutral conditions persisted across the tropical Pacific.
For the fifth consecutive month, ENSO-neutral conditions persisted across the tropical Pacific. However, sea surface temperatures (SSTs) in the vicinity of the Dateline continued to warm during August 2018. Preliminarily, the NINO4 Index is now on the El Niño side of neutral at +0.61°C (was +0.45°C last month) but the NINO3.4 Index remained in the neutral range at +0.28°C (was +0.47°C last month).
El Niño – Southern Oscillation (ENSO) neutral conditions continued across the tropical Pacific during July 2018. Sea surface temperatures (SSTs) in the central equatorial Pacific warmed for the fourth consecutive month and are currently slightly above average. The NINO3.4 is currently positive with a value of + 0.46°C for July 2018.
El Niño –Southern Oscillation (ENSO) neutral conditions continued across the tropical Pacific during June 2018. Sea surface temperatures (SSTs) in the central equatorial Pacific warmed for the third consecutive month and are currently slightly above average. The NINO3.4 is currently weakly positive with a value of + 0.27°C for June 2018.
ENSO-neutral conditions persisted in the tropical Pacific during May 2018. Sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean continued to warm during May and are now near or slightly above average. The NINO3.4 is currently close to zero (+0.01°C for May 2018).
Weak La Niña conditions transitioned to ENSO-neutral in the tropical Pacific during April 2018. Sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean remained below normal during April 2018, but continued to weaken relative to March values.
Weak La Niña conditions continued in the tropical Pacific during March 2018, but trends in low-level winds and in sub-surface ocean temperatures during the month indicate that the event is coming to an end.
Weak La Niña conditions continued in the tropical Pacific during February 2018, but the current state of the Ocean-Atmosphere system in the Equatorial Pacific indicates that it is now reaching its decay phase.
Weak La Niña conditions continued in the tropical Pacific during January 2018. Below average sea surface temperatures (SSTs) remained present in the central and eastern equatorial Pacific Ocean but warmed slightly compared to December 2017.
Weak La Niña conditions persisted in the tropical Pacific during December 2017
The tropical Pacific is still officially in a ENSO (El Niño Southern Oscillation) neutral state, but some indicators have leaned more towards La Niña conditions during the course of October 2017.
The tropical Pacific is still officially in a ENSO (El Niño Southern Oscillation) neutral state, but some indicators have leaned more towards La Niña conditions during the course of October 2017.
La Niña-like signals in the ocean–atmosphere system in the tropical Pacific Ocean have become more prominent and coherent in September 2017, although have not yet reached the thresholds required for a La Niña event to be declared.
ENSO (El Niño –Southern Oscillation) neutral conditions (neither El Niño nor La Niña) continued in the tropical Pacific during July 2017, mixed signals were again present this month. Some atmospheric patterns have been recently leaning more towards weak La Niña conditions.

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