SEA SURFACE TEMPERATURE (SST)
During September 2011, La Niña conditions strengthened as indicated by increasingly negative sea surface temperature (SST) anomalies across the eastern half of the equatorial Pacific Ocean. The weekly Nino indices continued their cooling trend and all are currently at or below –0.5°C. Consistent with this cooling, oceanic heat content (average temperature anomalies in the upper 300m of the ocean) remained below-average in response to a shallower thermocline across the eastern Pacific Ocean. Also, convection continued to be suppressed near the Date Line, and became more enhanced near Papua New Guinea. In addition, anomalous low-level easterly and upper level westerly winds persisted over the central tropical Pacific. Collectively, these oceanic and atmospheric patterns reflect the continuation of La Niña conditions.