Lets start by look at the sea surface temperature anomalies (differencea from normal) for a few areas in the tropical Pacific. The Nino3.4 area is often cited, and as you can see, this temperature anomaly has dropped from 3 to 1.5 C...a big drop. Even more dramatic is the decline in the temperature of the Nino1+2 area near the coast.
Even more dramatic, is the change in heat content of the upper ocean in the central and eastern tropical Pacific (see below), from well above normal to BELOW normal.
You can visualize this change by looking at vertical cross sections through the upper tropical Pacific ocean at several times during the past few months. The red area...a layer of warm water near the surface has greatly weakened and thinned.
So what will happen next winter? This is a bad time to ask the question, since the skill of our models, both dynamical (physics-based) and statistical, are poor during the early early to mid spring. Virtually all show a weakening of the strong El Nino of this winter, but some show a weak El Nino continuing, some showing near neutral conditions, and a few even suggesting a La Nina (cooler than normal waters).
In short, there is large uncertainty in our predictions for next winter and we will have to wait until June or July to have a better idea.