I've been reading on on some papers regarding ENSO (not necessarily newly published papers) but one thing I find intriguing regarding ENSO is how the ENSO event develops...and more specifically EL Ninio events. Obviously each event is different...different strengths, where the warmest anomalies are located, but this one paper I'm reading talks about HOW the event develops...I guess typically you would expect EL Nino's to develop as the easterlies weaken (or reverse in strong events) the WHWP spreads east...however, EL Nino events as of late have had a tendency to develop in the central Pacific.