Island Climate Update 235 - April 2020

El Niño Southern Oscillation (ENSO) neutral conditions continued during March 2020. The Southern Oscillation Index (SOI) was 0.5.

The NINO3.4 Index anomaly (in the central Pacific) for March was + 0.39˚C (in the neutral range). The warmest ocean waters with respect to average continued to be located in the west central Pacific, with the NINO4 region recording a monthly value of 0.69˚C. During March 2020, upper oceanic heat content near the Dateline decreased, while it increased farther east from about 140˚W to 110˚W. It is this warm pool of water, in the tropical north Pacific, that is expected to become a focal point for rainfall and convection during April-June.

Trade winds in March were weaker than normal east of the International Dateline from near 160˚W to 110˚W. Enhanced trade winds were present from the Dateline to about 160˚E. For most of April, enhanced trade winds (i.e.stronger than normal) are forecast to occur in the east central Pacific with weaker than normal trade winds in the west central part of the basin during the first half of the month. This will most likely lead to the persistence of the current SST pattern (warmer west, cooler east).

According to the consensus from international models, ENSO neutral conditions are most likely (81% chance) for the April-June period. For the July September period, the probability for ENSO neutral conditions is 53%. The probability of La Niña increases to 38% in October-December although ENSO neutral remains the most likely outcome (53% chance).

Download the full report: Island Climate Update - April 2020