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°C and 0.5°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.
April sees the beginning of the ice extent retracting. The interpretation of the anomaly is against the historical sea ice concentration map. Therefore a March forecast for an anomaly of 20 to 30 maybe against an area that historically has a concentration of 70 - 80 percent. The forecast for such an area would be between 28 and 40 percent.
Overall sea ice concentrations for the Arctic for April are well below normal for the Bering Sea plus the Barrents and Kara seas and near normal elsewhere other than east of Greenland where it should be a greater concentration than normal.