Highlights - December 2017
temperatures (SSTs) during December 2017 were below-average across the central and eastern equatorial
Pacific (Fig. T18,
Table T2). The latest monthly
Niņo indices were -0.3°C for the Niņo 4
for the Niņo 3.4 region, and -1.5°C for the Niņo 1+2 region (Table
T2, Fig. T5). The depth of the oceanic thermocline
(measured by the depth of the 20°C isotherm) was below-average over much of the
eastern equatorial Pacific (Figs. T15, T16), and
the corresponding sub-surface temperatures were 1-4°C below average (Fig. T17).
Also during December, the lower-level
trade winds were above-average over the western equatorial Pacific while the
upper-level westerly winds were near-average over much of the equatorial
Pacific (Table T1,
Figs. T20, T21).
Meanwhile, convection was enhanced over western equatorial Pacific and
suppressed over the central equatorial Pacific (Figs. T25, E3). Collectively, these oceanic and
atmospheric anomalies reflect La Niņa conditions.
For the latest status of the ENSO
cycle see the ENSO Diagnostic Discussion at: