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

MAY 2008

Oceanic indices indicated a further weakening of La Niña during May 2008 (Table T2). Negative SST anomalies weakened in the central and east-central equatorial Pacific Ocean , while positive SST anomalies were confined to parts of the eastern equatorial Pacific (Fig. T18). The latest weekly Niño-3.4 index was -0.6°C, and the Niño-4 index was -0.8°C.

Accompanying these surface conditions, the oceanic thermocline was near normal across the equatorial Pacific east of 150°W during May, and continued to deepen west of the Date Line (Fig. T16). Consistent with this structure, sub-surface temperatures at thermocline depth were above average (+1°C to +4°C) across the eastern equatorial Pacific and in the area west of the Date Line (Fig. T17).

Enhanced low-level easterly winds and upper-level westerly winds continued across the central equatorial Pacific during May (Figs. T20, T21, Table T1). Convection remained suppressed throughout the central equatorial Pacific and enhanced over the far western Pacific (Figs. T25, E3). 

Collectively, these atmospheric and oceanic conditions continue to indicate an ongoing, but gradually weakening, La Niña.

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