It does look like a good WWB will occur the next 1-2 weeks, which should help the ENSO regions see some warming, but as usual, the question is can it sustain itself. We will have to see going forwards, but with enough of a WBB we will push into weak El nino considering all of the warm subsurface water.
El Niño conditions? Or an El Niño by the official definition? As I’m sure you already know, the latter depends on circulatory tendencies on frequencies much lower than a single WWB event.
FWIW, it’s not just the frequency or intensity of the wind stress forcing, but also how it times with the relatively fixed intertia/resonance-frequency of the thermocline/KW/ERW cycle itself (which is tightly constrained via mechanical fluid-dynamic limits).
If the wind stress forcing and thermocline/KW inertia are out-of-phase, it’s very difficult to pull off a coherent ENSO event. Often times, poorly synchronized years (such as this one and 2014/15) precede larger events of a similar sign in subsequent years, given they’re usually reflections of slower-evolving macroscale teleconnective boundary conditions.
Which is why I’ve considered this year to be false start prequel to a stronger niño in 2019/20 (or possibly 2020/21 depending on how the annular modes/AAM budget responds this winter).