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ENSO Quick
Look IRI ENSO Update / Forecast Technical ENSO Update IRI Probabilistic ENSO Forecast ENSO Prediction Plume Monthly archive ENSO Update19 February 2009SummaryThe equatorial Pacific has exhibited weak but clear La Niña conditions since December 2008, and such conditions continue as of mid-February. There is a 55-60% probability of La Niña conditions persisting during the February-April season, decreasing to 30-35% for the April-June season as near-neutral conditions become most likely.General Discussion
La Niña conditions returned in early December according to the
eastern-central Pacific NINO3.4 SST index.
Near average conditions had reigned in the tropical Pacific since
early June, following the 2007/08 La Niña event.
Atmospheric anomalies had suggested that the tropical Pacific should
have been cooling since late August 2008, when the Southern Oscillation index
became persistently positive, and low-level equatorial winds became
persistently easterly. The oceanic response to
these atmospheric conditions lagged by three to four months. |
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