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IRI ENSO Update / Prediction
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ENSO Prediction Plume
17 November 2011
SummaryWeak La Niña conditions re-emerged in August after a brief period of ENSO-neutral conditions following the ending of the significant 2010-11 La Niña. The current event has slowly strengthened and is currently of weak to moderate strength. For the November-January season currently in progress, there is an approximately 74% probability for continuing La Niña conditions, a 26% probability for returning to neutral conditions, and virtually no chance for the development of El Niño conditions. Weak to moderate La Niña conditions are the most likely scenario for the remainder of 2011, into the first couple of months of 2012.
In mid-November 2011, the NINO3.4 SST anomaly index was at -0.9 C from average,
indicative of weak La Niña conditions. Sea temperatures below the ocean surface
remain below average, and zonal wind anomalies in the equatorial Pacific feature a
somewhat enhanced strength of easterlies, although recently there was a notable
interruption due to intraseasonal variability. The Southern Oscillation Index is slightly
above average, at a borderline to weak La Niña level. These observations indicate
weak to nearly moderate La Niña conditions, as has been the case since early October.