In April, the India Meteorological Department made two important forecasts for the upcoming monsoon. One, that El Niño conditions – the unusual warming of ocean surface water that can cause reduced rainfall – were likely to develop during the monsoon. Two, despite these conditions, the monsoon will be “normal”, with the south peninsula expecting normal to above normal amounts of rain, and north-west India expecting normal or below normal rainfall.
However, by the end of June, the situation on the ground looked very different from these forecasts. The geographical distribution of rainfall was the opposite of what had been forecast: north-west India saw 42% excess rainfall in June, while the southern peninsula experienced 45% below normal rainfall, along with a 6% deficiency in central India, and an 18% deficiency in east and north-east India.
The April forecast of the IMD followed the template of long-range forecasting, which can be done as many as two years in advance. For the monsoon – a crucial season during which India gets 70% of its annual rainfall – the IMD issues forecasts up to three months in advance. Predicting rainfall between June to September, it presents a general trend of expected monsoonal conditions.
But closer to the onset of the monsoon, smaller variations can mould how the…
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