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The LPA of the seasonal rainfall over the country as a whole, based on the 1971-2020 data, is 87 cm. Rainfall between 90-95% of the LPA is considered ‘below normal’.IMD’s forecast shows 31% probability of ‘below normal’ rainfall, whereas 35% probability of deficient rainfall (below 90% of the LPA) — a clear indication of the higher probability of less than normal rainfall in the country.Though the met department will come out with more specific updated forecast on spatial distribution of rainfall during the season (June-Sept) in the last week of May, the ‘probability forecast’ map released by it on Monday clearly shows ‘below normal’ rainfall in the ‘monsoon core zone’ of the country — the zone which comprises of most of the central and west India which largely depends on rains for farming operation. This scenario is most likely to impact irrigation, drinking water in arid and semi-arid zones, reservoirs’ capacity and hydro-power potential at a time when the country is already staring at high input (diesel and fertilisers) costs for farming operations and overall high energy costs due to war in West Asia.Less rain not only adversely impacts the acreage of kharif crops (summer sown) but also rabi crops (winter sown) due to less moisture content in the soil and less water for irrigation in the reservoirs, affecting overall food grain output even as the country has, over the years, taken multiple measures to make its farm sector drought-proof.Under the possible development of El Niño – climate conditions associated with warming of the ocean surface in the central and eastern tropical Pacific Ocean – this year, there is a high possibility of depressed rainfall during the second half of the monsoon (Aug-Sept). Other factors, such as the Indian Ocean Dipole (IOD), may, however, come as a saviour. Positive IOD leads to more rainfall. So, we expect that this will counter the impact of El Niño during the second half of the monsoon season,” said Mohapatra.
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At present, neutral IOD conditions are present over the Indian Ocean, and the latest climate models forecast indicates that the positive IOD conditions are likely to develop towards the end of the southwest monsoon season.Snow cover over the northern hemisphere also impacts the monsoon. IMD explained that the snow cover extent during the last three months (Jan to March) was slightly below normal. “Winter and spring snow cover extent over the Northern Hemisphere, as well as Eurasia, has a general inverse relationship with the subsequent southwest monsoon seasonal rainfall over the country,” it said.
