Island Climate Update 237 - June 2020

During May the NINO3.4 Index anomaly (in the central Pacific) for May was +0.01˚C, with upper oceanic heat content continuing to decrease across the equatorial Pacific. Anomalies were below average east of the International Dateline, suggestive of an ocean system that may be trending towards La Niña.

Rainfall and convection was above normal in the far western equatorial Pacific. This was associated with a mid month pulse of convective activity that generated two tropical cyclones in the Indian Ocean. Otherwise, the pattern was consistent with an ENSO neutral state.

Trade winds during May were stronger than normal across most of the equatorial Pacific, particularly in the east central part of the basin. This pattern is expected to continue over the next 1 2 months, likely leading to continued cooling in the west central Pacific.

In the subsurface ocean, cooler than average temperatures continued to push eastward during May. Some surfacing of these cooler waters was evident in the central and eastern part of the basin. Subsurface anomalies decreased to 3 C near 100 m depth, a decrease of 1 2 C compared to April. This continues to give validity to the idea that oceanic La Niña conditions might arrive later in 2020 as some models suggest.

According to the consensus from international models, ENSO neutral conditions are most likely (71% chance) for the June August period. For the September November and December 2020 February 2021 periods, the probability for ENSO neutral conditions is 44% for both, with the probability for La Niña increasing to 31% by spring 2020.

Download the full report: Island Climate Update - June 2020


Research subject: ClimateWeather