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ENSO Alert System Status: El Niño Advisory
Synopsis: Weak El Niño conditions are likely to continue through the Northern Hemisphere spring 2019 (~80% chance) and summer (~60% chance).
El Niño conditions strengthened during February 2019, as above-average sea surface temperatures (SSTs) increased across the equatorial Pacific Ocean and the associated atmospheric anomalies became increasingly well-defined. The SST index values in the Niño3, Niño3.4 and Niño4 regions all increased during February, with the latest weekly values near +1C in each region. The anomalous upper-ocean heat content (averaged across 180°-100°W) increased appreciably during February, due to an increase in above-average temperatures at depth in association with a downwelling equatorial oceanic Kelvin wave. Enhanced equatorial convection prevailed near the Date Line, while suppressed convection was observed over Indonesia. Low-level wind anomalies were westerly in the central Pacific Ocean, while upper-level wind anomalies were mostly westerly over the far western and far eastern Pacific. The equatorial and traditional Southern Oscillation Index values were both negative (-1.4 standard deviations). Overall, these features are consistent with weak El Niño conditions.
The majority of models in the IRI/CPC plume predict a Niño 3.4 index of +0.5C or greater through the Northern Hemisphere early autumn 2019. Given the recent downwelling Kelvin wave, and the increase in both the SSTs and subsurface ocean temperatures, most forecasters expect positive SST anomalies to persist across the central and eastern Pacific for at least the next several months. During that time, forecasters predict the SST anomalies in the Niño 3.4 region to remain between +0.5C and +1.0C, indicating weak El Niño conditions. However, because forecasts made during spring tend to be less accurate, the predicted chance that El Niño will persist beyond summer is currently about 50%. In summary, weak El Niño conditions are likely to continue through the Northern Hemisphere spring 2019 (~80% chance) and summer (~60% chance); click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period.