Tropical Highlights

  Table of Atmospheric Indices  (Table 1)

  Table of Oceanic Indices  (Table 2)

  Time Series

  Time-Longitude Sections

  Mean & Anomaly Fields

  Appendix 1: Outside Contributions

Tropical Highlights

APRIL 2010

El Niño weakened during April 2010, as the sea surface temperature (SST) anomalies decreased across most of the equatorial Pacific Ocean (Fig. T18).  The latest monthly SST indices were +0.7°C for both the Niño-3.4 and the Niño-3 regions. (Table T2, Fig. T5). Consistent with this evolution, the oceanic thermocline (measured by the depth of the 20°C isotherm) was shallower than average across the central equatorial Pacific (Figs. T15, T16), with sub-surface temperatures remaining below average in that region (Fig. T17).

Also during April, equatorial low-level easterly winds remained stronger than average over the western Pacific, while the upper-level westerly wind anomalies persisted across the central Pacific (Table T1, Figs. T20 and T21). This wind pattern was associated with enhanced convection over Indonesia and suppressed convection across the equatorial Pacific, south of the equator (Figs. T25, T26 and E3). Collectively, these oceanic and atmospheric anomalies reflect a weakening El Niño.

For the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at:   

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html