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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 November 2009SummaryEl Niño conditions are strengthening in the equatorial Pacific. For the Nov-Jan and Dec-Feb seasons there is an approximately 95% probability of maintaining El Niño conditions. Probabilities for El Niño stay at or above 90% through the Feb-Apr season, decreasing to 55% by Apr-Jun season and to the climatological probability of 25% by the Jul-Sep season.General Discussion
By mid-November 2009, the NINO3.4 SST anomaly index had risen
to values indicative of the moderate El Niño category.
Up until recently, the event had maintanined only a weak magnitude,
but strong and persistent westerly wind anomalies during September,
and especially those during October, substantially increased the SST anomalies
in the central and eastern equatorial Pacific. Those wind anomalies
also had a substantial impact on the sub-surface ocean, deepening the
thermocline. This could allow for further growth and will certainly provide
several months of persistence to the current event. The wind anomalies
in the western Pacific have become easterly since early November, suggesting
that much of the rrecent wind anomalies are due to passage of a very strong
MJO, or intraseasonal variability. El Niño conditions are expected
to persist through the end of the calendar year and possibly a few
additional months. |
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