SEA SURFACE TEMPERATURE (SST)
During March and April, positive sea-surface temperature (SST) anomalies extended in a horseshoe pattern from the central North Pacific to the central South Pacific, while negative anomalies extended from the west coast of North America to the Gulf of Alaska. In the past four weeks, the trend in SST anomalies was positive (warming) across the equatorial Pacific Ocean, especially in the far eastern Pacific. Upper ocean heat content anomalies have weakened since late December 2008 and have recently become positive. From March through mid-April, negative sub-surface temperature departures weakened east of the Date Line, while positive departures expanded eastward to near 100°W.