Why is the Indian monsoon so slippery?

The monsoon of the Indian subcontinent is also shaped by the heating of the Tibetan plateau, the shape of continents and mountains, Eurasian snow cover, temperature difference between eastern and western flanks of the Indian ocean, and, arguably the most important, El Niño (“little boy” in Spanish as this event occurs around Christmas), a weather event triggered by a greater heating of the eastern Pacific near Ecuador than its western counterpart. A strong El Niño, more often than not, implies a weak monsoon. In the last 100 years, 19 out of 43 deficient monsoon years were linked to a strong El Niño, while six went against the dominant pattern. This is one of the many irregularities characteristic of the monsoon that makes long-range forecasting extremely difficult.