Tropical Highlights – April 2012

 

 

 A transition from La Niña to ENSO-neutral conditions occurred during April 2012, as reflected by by a decreased magnitude of the negative surface temperature (SST) anomalies in the central equatorial Pacific, along with continued positive SST anomalies in the eastern equatorial Pacific (Fig. T18, Table T2). The latest monthly Niño indices were -0.4°C for the Niño 3.4 region and +1.3°C for the Niño 1+2 region (Table T2, Fig. T5). Consistent with these conditions, the depth of the oceanic thermocline (measured by the depth of the 20°C isotherm) became near-average in the east-central equatorial Pacific and above-average in the far eastern equatorial Pacific (Figs. T15, T16).

Also during April, the equatorial low-level easterly trade winds were much weaker over the central and west-central equatorial Pacific (Table T1, Fig. T20). Suppressed convection was seen across the equatorial Indian Ocean and Indonesia (Figs. T25, E3). Collectively, these oceanic and atmospheric anomalies reflect a transition from La Niña to ENSO-neutral 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