PMEL climate scientists describe in a recently published paper the relationship between the 2014-15 failed El Niño and this year’s monster El Niño as well as any similarities between the past strong El Niño’s. They examined changes in sea surface and sub-surface temperatures, winds, and volumes of warm water in the Pacific Ocean from 2014 to 2016.
What they found was that the highly anticipated 2014-15 El Niño event failed due to unusually strong easterly winds in the summer of 2014 which prevented the warm surface water from shifting eastward as seen in a typical El Niño events and left a reservoir of warm water below the ocean’s surface. This reservoir of warm water combined with strong westerly winds that appeared and continued throughout the spring and summer of 2015 led to the monster El Niño. They found a similar series of events that led to the 1991-92 El Nino event.