Monsoon, which plays a significant role in India’s agriculture and thereby the economy, has so far eluded the central and northern states of the country. This despite a forecast of a normal monsoon by the Indian Meterological Department (IMD). So why has the forecast gone wrong?

The unpredictable nature of the monsoon means one can only provide an accuracy of 55-60% even with the best of technology, Mrutyunjay Mohapatra, IMD director general told the Times of India. The department had forecast a normal monsoon but by June end Kerala had already recorded 36% rain deficiency. Similarly, it was forecast that monsoon will hit Delhi by June 15. And it is July 5 and Kerala is yet to witness monsoon showers.

“It is extremely difficult to forecast how a monsoon will progress over a period of more than 15 days,” Mohapatra said. The reliance on human intervention makes it even more difficult, he added.

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Let’s take a look at what the monsoon mean to Indian econmy and how it is predicted:

Why is the monsoon important?

The southwest monsoon, which accounts for 70-75 % of the annual rainfall, plays a significant role in India’s agriculture sector. The sector contributes around 15-17 % to the GDP and accounts for 55-60 % jobs at any given time in the job market. Several sectors, such as agriculture products packing, exports, agri products manufacturers, keenly follow monsoons to devise startegies.

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What is a normal monsoon?

During a normal monsoon from June to September, rainfall between 96% and 104% of a 50-year average is expected, according to the IMD. Rains below 90% of the average is categorised as deficient. Is rainfall crosses 110% of the average, it is categorised as excessive monsoon.

How have IMD predictions fared?

The southwest monsoon season has rarely been normal in the past few years even though the IM) has predicted a normal monsoon every year for the past six years. In 2018, monsoon was 9% deficient while the IMD had predicted a 2% excess. In 2019, the IMD got the prediction wrong by 14 % and by 7% in 2020. In 2015, IMD had predicted a rainfall deficit of 12 %, the actual deficit was 14 %.

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How is the monsoon forecast?

It is predicted with the combination machinary, models and human skills. It involves continuous monitoring of surface and upper air meteorological observations, real time monitoring of the monsoon using remote sensing techniques like satellite and radars, analysis of meteorological charts and guidance from various national and international weather forecasting models at different spatio-temporal scales.

IMD issues short forecasts for 5 days. These are based on several national and international weather forecasting model guidance and expertise from the scientists.