ENSO Alert System Status: Final La Niña Advisory
Synopsis: ENSO-neutral conditions have returned and are favored to continue through at least the Northern Hemisphere spring 2017.
La Niña conditions are no longer present, with slightly below-average sea surface temperatures (SSTs) observed across the central equatorial Pacific and above-average SSTs increasing in the eastern Pacific. The latest weekly Niño index values were -0.3°C in the westernmost Niño-4 and Niño- 3.4 regions, and +1.5°C in the easternmost Niño-1+2 region. The upper-ocean heat content anomaly increased during January and was slightly positive when averaged across the eastern Pacific, a reflection of above-average temperatures at depth. Atmospheric convection remained suppressed over the central tropical Pacific and enhanced over Indonesia. The low-level easterly winds were slightly enhanced over the western tropical Pacific, and upper-level westerly winds were near average. Overall, the ocean and atmosphere system is consistent with ENSO-neutral conditions.
Most models predict the continuation of ENSO-neutral (3-month average Niño-3.4 index between -0.5°Cand0.5°C)through the Northern Hemisphere summer. However,a few dynamical model forecasts, including the NCEP CFSv2, anticipate an onset of El Niño as soon as the Northern Hemisphere spring (March-May 2017). Because of typically high uncertainty in forecasts made at this time of the year for the upcoming spring and summer, and the lingering La Niña-like tropical convection patterns, the forecaster consensus favors ENSO-neutral during the spring with a ~60% chance. Thereafter, there are increasing odds for El Niño toward the second half of 2017 (~50% chance in September-November). In summary, ENSO-neutral conditions have returned and are favored to continue through at least the Northern Hemisphere spring 2017 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).