Synopsis: ENSO-neutral conditions are favoured to continue through at least the Southern Hemisphere fall 2017, with increasing chances for El Niño development into the spring.
ENSO-neutral conditions continued during February, with near-average sea surface temperatures (SSTs) across the central equatorial Pacific and above-average SSTs in the eastern Pacific. The latest weekly Niño index values were near zero in the Niño-4 and Niño-3.4 regions, and +0.4 and +2.2°C farther east in the Niño-3 and Niño-1+2 regions, respectively. The upper-ocean heat content anomaly increased during February and was slightly positive when averaged across the central and eastern Pacific, a reflection of generally above-average temperatures at depth. Atmospheric convection remained suppressed over the central tropical Pacific and enhanced over the Maritime Continent. The low-level easterly winds were slightly enhanced over the western tropical Pacific and were weaker than average over the eastern Pacific. Also, upper-level westerly winds were anomalously easterly over portions of the western and eastern Pacific. 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 early Southern Hemisphere winter (May-July). However, some dynamical model forecasts, including the NCEP CFSv2, anticipate an onset of El Niño as soon as the late Southern Hemisphere autumn (March-May 2017). Because of typically lower skill in forecasts made at this time of the year, and the lingering La Niña-like tropical convection patterns, the forecaster consensus favors ENSO-neutral during the autumn (March-May) with a ~75% chance. Thereafter, there are increasing odds for El Niño toward the second half of 2017 (50-55% chance from approximately July-December). In summary, ENSO-neutral conditions are favored to continue through at least the Southern Hemisphere autumn 2017, with increasing chances for El Niño development into the spring.
Almost all of the North Island should be slightly warmer than normal.
Near normal in the north and slightly to moderately drier in the Bay of Plenty.
Almost all of the South Island should be moderately warmer than normal.
Slightly drier across the west and near normal to slightly wetter in the east.