Island Climate Update 227 - August 2019

During July 2019, SSTs dipped below El Niño thresholds in the central Pacific for the first time in 5 months. The NINO3.4 Index anomaly (in the central Pacific) for the month of July was +0.54˚C (the threshold for El Niño is +0.70˚C). Meanwhile, warmth was steadfast in the NINO4 region (western Pacific) with a monthly value of +0.79˚C.

The Southern Oscillation Index (SOI) was -0.5 during July. The conventional threshold for El Niño wasn’t reached (SOI values below -1.0 for three consecutive months), but a weakly coupled central Pacific El Niño remains present.

Across the tropical Pacific, rainfall and convection patterns remained generally consistent with a weak, central Pacific El Niño. Rainfall was above normal just west of the International Dateline as well as between 10-20˚N and 10-20˚S in the central Pacific.

The probability for oceanic El Niño conditions, according to the consensus from international models, is 38% for the August – October 2019 period with a 56% chance for the development of ENSO-neutral conditions. This Is the first time since July 2018 that ENSO neutral is the most likely outcome. For the November 2019 - January 2020 period, the probability for El Niño is 47% and neutral 42%. For the February – April 2020 period, the probability for El Niño is 51% and neutral 46%.

Download the full report: Island Climate Update August 2019 [2.3 MB PDF]