Niņa continued to weaken during April 2011 as the magnitude of the negative sea
surface temperature anomalies decreased further across much of the equatorial
Pacific Ocean (Fig.
T18, Table T2).
The latest monthly Niņo indices were -0.8°C for the Niņo
3.4 region and +0.2°C for the Niņo
1+2 region (Table T2,
Consistent with these conditions, the oceanic thermocline (measured by
the depth of the 20°C
isotherm) remained slightly deeper than average over the eastern equatorial
Pacific (Figs. T15 and
T16), with sub-surface temperatures
above average in this region (Fig. T17).
the atmospheric circulation patterns during April continued to show La Niņa
equatorial low-level easterly trade winds remained stronger than average over
the western and central Pacific (Table T1,
while convection remained enhanced over Indonesia and suppressed across the
western and central equatorial Pacific (Figs.
T25 and E3).
Collectively, these oceanic and atmospheric anomalies reflect a weakening La Niņa.
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at: