Synopsis: ENSO-neutral conditions have returned and are favoured to continue through at least the Southern Hemisphere fall 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°C and 0.5°C) through the Southern Hemisphere winter. However, a few dynamical model forecasts, including the NCEP CFSv2, anticipate an onset of El Niño as soon as the Southern Hemisphere fall (March-May 2017). Because of typically high uncertainty in forecasts made at this time of the year for the upcoming fall and winter, and the lingering La Niña-like tropical convection patterns, the forecaster consensus favors ENSO-neutral during the fall 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 Southern Hemisphere fall 2017.
Almost all of the North Island should be slightly warmer than normal.
Near normal to slightly wetter in the East Cape and northern Hawkes Bay.
Almost all of the South Island should be moderately warmer than normal.
Near normal to slightly drier across much of the west and near normal in the east.