El Nino raises chances of intense daily rain across central India, says new study

Unlike El Nino’s weakening influence on India’s average summer rainfall in recent decades, its impact on extremes has remained comparatively steady over time, though with some regional shifts.

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Although El Nino suppresses overall monsoon season rainfall across India, a new study finds that it also, counter-intuitively, sharply increases the likelihood of extreme daily downpours in the country’s wetter regions.

Over a vast central swath, stretching from Gangetic West Bengal and Odisha in the east to Gujarat and Rajasthan on the west, the likelihood of such high-intensity rain is about 50% higher in the El Nino summers, compared to La Nina years.

El Nino, an unusual warming of the Pacific Ocean, plays havoc with weather patterns across the globe. It is generally adverse for the south west monsoon in India though there are a few exceptions. Its opposite La Nina or cooling of the Pacific is good for monsoon.

During El Nino years, warmer Pacific waters trigger unusual patterns of rising and sinking air, producing a large-scale suppression of seasonal rainfall across the Indian subcontinent.

In India’s typically drier regions, this results in fewer rainy days and weaker showers, compounding their dryness.