There is a 65% chance that El Niño will form and continue through the Northern Hemisphere spring 2019. NOAA Climate Prediction Center reports that ENSO-neutral continued during December 2018, despite widespread above-average sea surface temperatures (SSTs) across the equatorial Pacific Ocean. (Figure 1).
In the last couple of weeks, all four Niño indices decreased. Positive subsurface temperature anomalies also weakened, but above-average temperatures continued at depth across most of the equatorial Pacific Ocean. Regardless of the above-average SSTs, the atmospheric circulation over the tropical Pacific has not yet shown clear evidence of coupling to the ocean. The late winter and early spring tend to be the most favorable months for coupling, so forecasters still believe weak El Niño conditions will emerge shortly. However, given the timing and that a weak event is favored, significant global impacts are not anticipated during the remainder of winter, even if conditions were to form.