SEA SURFACE TEMPERATURE (SST)
During December 2011, below-average sea surface temperatures (SST) associated with La Niña continued across the eastern and central equatorial Pacific Ocean. The weekly SST index in the Niño-3.4 region remained near –1.0°C throughout the month, indicating a weak to moderate La Niña. The oceanic heat content (average temperature in the upper 300m of the ocean) anomalies strengthened across the eastern Pacific, reflecting a large area of below-average temperatures in the subsurface. In the atmosphere, anomalous low-level easterly and upper-level westerly winds strengthened over the central and west-central Pacific. Collectively, the ongoing oceanic and atmospheric patterns reflect the continuation of a weak to moderate La Niña.