About the role of Westerly Wind Events in the possible development of an El Niño in 2014

Similarities between early 1997 and 2014 has prompted climate scientists to wonder if an El Niño matching the 1997 “El Niño of the century” could develop in 2014. Until April 2014, the equatorial Pacific exhibited positive heat content anomalies along with an eastward warm pool displacement similar to those found during the onset of strong El Niño events. Yet in July 2014, the warm pool had retreated back to its climatological positions and equatorial temperature anomalies were much weaker than in mid‐1997. Dedicated oceanic simulations reveal that these weak interannual anomalies can be attributed to differences in Westerly Wind Event (WWE) sequences. In contrast with 1997, the lack of WWEs from April to June significantly limited the growth of eastern Pacific anomalies and the eastward warm pool displacement in 2014. With the absence of additional WWE activity, prospects for a mature El Niño in late 2014 are fading. Key Points Westerly wind events were crucial in the development of the 1997 El NiñoEarly 2014 conditions looked like 1997 but westerly wind activity stoppedThis lack of events after April 2014 prevented an El Nino like 1997