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ENSO
Quick Look IRI ENSO Update / Forecast Technical ENSO Update Summary of Model Forecasts Monthly archive ENSO Update19 May 2005SummarySea surface temperatures in the eastern and central equatorial Pacific are currently near-normal or ENSO-neutral, although they remain above-average throughout much of the equatorial Pacific. Based on the latest observations and forecasts, it is 70% likely that neutral conditions will prevail over the May-Jun-Jul 2005 season.General DiscussionDuring April 2005, sea surface temperatures (SSTs) were within the range of near-normal conditions. Although the SST anomalies in the central Pacific are currently classified as near-normal, the anomalies were above-average and more than 0.5 degree C warmer than average over parts of the western and eastern equatorial Pacific. During April, the trade winds near the equator remained close to their average strength for this time of year. However, large positive temperature anomalies developed in the eastern equatorial Pacific near the end of April as a large sub-surface Kelvin wave reached the far eastern Pacific, initiated from strong westerly wind anomalies in the western/central Pacific during February 2005. By mid-May 2005, the sub-surface anomalies are largely eroded, and the positive SST anomalies are diminishing. Out of a large set of dynamical and statistical forecast models, approximately 30% predict sea surface temperatures at weak El Niño levels for the May to July period in the central Pacific. Overall, based on model forecasts and current observations of the ocean surface and subsurface, the chances for returning to El Niño conditions are approximately 30% through July 2005, increasing very slightly thereafter. The likelihood of maintaining neutral conditions is approximately 70% through July 2005, and neutrality remains the most likely scenario through the end of 2005. The probability of a La Niña developing between now and July 2005 is near zero, rising to 5% thereafter.Note 1 - Only models that produce a new ENSO forecast every month are included in the above statement.
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