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ENSO Quick
Look IRI ENSO Update / Forecast IRI Probabilistic ENSO Forecast Technical ENSO Update ENSO Prediction Plume Monthly archive ENSO Update17 August 2006SummaryNeutral conditions exist in the tropical Pacific. As of mid-August sea surface temperatures (SSTs) are near 0.5C above average throughout much of the equatorial Pacific, and are approximately 1.0C above-average near the dateline. There appears to be a warming trend in the equatorial Pacific over the last couple months; however, it is still uncertain whether temperatures will warm to the level of an El Niño event in the coming seasons. Based on the latest observations and forecasts, the probability of neutral conditions continuing through the August-September-October 2006 season is approximately 60%.General DiscussionIn recent months, equatorial SSTs have been gradually increasing due largely to persistent westerly wind anomalies over the west Pacific. The western and central equatorial Pacific have warmed to about 0.5 deg C above average since mid-May 2006, and a localized anomaly of about 1.0C exists near the dateline. The SSTs in the far eastern equatorial Pacific have varied between about 0.5-1.0C above average over the last several weeks, although the spatial structure of the anomalies has been changeable from week to week. The equatorial heat content is also above-average and has been increasing over the last several months, relative to the 1970-2001 climatology period. The sub-surface pertubations to the temperature field, associated with the increasing heat content, and resulting from the westerly wind anomalies, have the potential to further increase SSTs as they move toward the eastern Pacific. However, these sub-surface anomalies will likely need further reinforcement if they are to contribute to development of an El Niño event in the eastern Pacific.The observations and models suggest that neutral conditions will most likely be in place through 2006. Out of a large set of dynamical and statistical forecast models, most predict neutral conditions continuing throughout 2006. Overall, based on model forecasts and current observations of the ocean surface and subsurface, the probability of a La Niña is much less than the climatologically expected odds of 25%. The probability of developing El Niño conditions is between 35-40%, and that of maintaining neutral conditions through the end of 2006 is 60%. Note 1 - Only models that produce a new ENSO forecast every month are included in the above statement.
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