Island Climate Update 222 - March 2019
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.
The atmosphere continued to respond to a warm pool of water in the central and western tropical Pacific Ocean. This was reflected by well above normal rainfall during February near the Dateline and below normal rainfall over the Maritime Continent (Indonesia and north of Australia).
Central Pacific El Niño conditions are now occurring as the ocean and atmosphere have been weakly coupled for a third consecutive month. Traditionally, this occurs farther east toward South America and during the early summer season.
The Southern Oscillation Index (SOI) decreased substantially from near 0.0 in January to a value of -1.2 in Februaryand is currently in the El Niño territory.According to the consensus from international models, the probabilityfor oceanic El Niño conditions is 76% for the March–May period. This is an increase from 66% last month. Beyond this, for the June to August period, the probability for oceanic El Niño conditions increased to 61%, up from 48% last month.
Oceanic El Niño remains the mostly likely outcome for the March to May period at 48%. This continues to suggest the potential for a ‘protracted’ event (multi-year duration).