How far in advance can we predict the existence and the intensity of an El Niño event?
Accurately? In terms of timing and magnitude, hardly at all. In terms of saying that an “equatorial warm event” (only vaguely defined in magnitude) will start within a particular six-month time frame, we can typically foresee that up to a year in advance. Some prediction models succeed in doing this on one event and then go bust on the next. There’s a good example of that in 1997. Accordingly, we have come to rely more on a “consensus forecast” of many models rather than on any one model. But the long-lead accuracy still leaves a lot to be desired. Most models correctly anticipated a “warm event” for the 1997/98 winter as early as one year earlier. However, none of the predictions anticipated that strong anomalies would already be in place by June, 1997, while their predicted magnitudes were small compared with what actually occurred.
