Tropical Highlights – February 2012

 

 

 La Niña weakened during February 2012 as reflected by the development of positive sea surface temperature (SST) anomalies in the eastern equatorial Pacific and by a decreased magnitude of the negative SST anomalies in the central equatorial Pacific (Fig. T18, Table T2). The latest monthly Niño indices were -0.7°C for the Niño 3.4 region and +0.2°C for the Niño 1+2 region (Table T2, Fig. T5). Consistent with these conditions, the oceanic thermocline (measured by the depth of the 20°C isotherm) remained shallower than average in the east-central equatorial Pacific (Figs. T15, T16), although corresponding sub-surface temperatures were only 1-3°C below average (Fig. T17). These departures are several degrees warmer than the large negative values seen during November-January.

Also during February, the equatorial low-level easterly trade winds were stronger than average over the central and west-central equatorial Pacific (Table T1, Fig. T20).  Convection remained suppressed in the western and central equatorial Pacific and enhanced across the Indian Ocean and the Philippines (Figs. T25, E3). Collectively, these oceanic and atmospheric anomalies reflect a weakening of La Niña conditions.

 

 

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