El Niño continued during February and has around an 80% chance of persisting through April. However, ENSO neutral conditions are favoured to develop during May-July 2024.
The monthly NINO3.4 Index anomaly (in the centralequatorial Pacific) at the end of February was +1.55˚C, within the range of a strong El Niño (classified when the NINO3.4 Index is greater than +1.5˚C). Although the current El Niño event is past its peak oceanic intensity, atmospheric patterns will likely continue to show El Niño-like tendencies in the months ahead.
TheSouthern Oscillation Index (SOI) was in the El Niño range during February (-1.1) and the neutral range during December-February (-0.4). This suggests that El Niño’s reflection in the atmosphere has been atypical, particularly considering the oceanic intensity.
Trade wind strength was was slightly below normal across most of the equatorial Pacific during February and greatly reduced from normal in the off-equatorial South Pacific, where winds blew from the west.
During mid-March, an area of enhanced trade winds is forecast in the west-central equatorial Pacific, a reversal of February’s pattern and the one that dominated over recent months.
In February, the subsurface equatorial Pacific was cooler than average below 100 m depth across most of the basin. Above average temperatures were confined to the upper 50-100 m. Upper-oceanic heat content returned to near normal values in the equatorial Pacific aside from the far eastern part of the Pacific, suggesting that the ‘cool pool’ of sub-surface water had significantly eroded warmth associated with El Niño.
A marine heatwave remains active between Vanuatu and Fiji, as well as island groups farther east including the northern Cook Islands.
During mid-March, a pulse of the Madden-Julian Oscillation may increase the chance for tropical cyclone development between Vanuatu and the Coral Sea. With an El Niño event ongoing, all met services should remain vigilant.