Why are El Nino and La Nina events difficult to forecast correctly up to a year in advance? What hinders our ability to predict ENSO events? Why can we predict El Nino events at all? The predictability of ENSO is an intriguing problem because there exist both mechanisms that enhance our ability to predict events and mechanisms that hinder our ability to predict events. Many months prior to El Nino events, the subsurface waters along equatorial Pacific become unusually warm. Given an atmospheric wind trigger (visualize how blowing on your hot coffee induces waves in your coffee cup), this warm signal slowly propagates to the east via equatorial waves and the onset of an El Nino event begins. This slow ocean mechanism is why we can predict El Nino events. That said, the ocean's response to random winds associated with atmospheric weather make it difficult to predict the amplitude of El Nino events.