Island Climate Update 228 - September

Upper-oceanic heat content anomalies continued to decrease, but remained slightly above average in the west-central equatorial Pacific. In the eastern part of the basin, heat content was below normal for the time of year. Overall, this reflects ENSO neutral conditions, but with a slight lean toward El Niño-Modoki (central Pacific El Niño).

During August, above normal rainfall occurred from the eastern Maritime Continent into the western Pacific, with below normal rainfall just north of the equator in the central Pacific. This remained broadly consistent with El Niño Modokiconditions.

Trade winds were slightly weaker than normal in the eastern Pacific and slightly stronger than normal in the west-central Pacific. During September, reduced trades are forecast to west of the International Dateline, which may help to sustain the warm pool of water in the NINO4 region.

On the other hand, stronger than normal trade winds are expected in the east-central tropical Pacific, which may lead to additional cooling of SSTs.

According to the consensus from international models, oceanic ENSO-neutral conditions are most likely at 59% chance for the September–November period with El Niño at 33% chance. For the December 2019–February 2020 period, the probability for neutral conditions is 49% with the chance for El Niño increasing to 41%. For the March–May 2020 period, the probability for neutral conditions and El Niño is 55% and 43%, respectively.

Download the full report: Island Climate Update September 2019 [652 KB PDF]