NEW DELHI: In a big relief to the country, the India Meteorological Department forecast a normal monsoon with 99 per cent chances of good rainfall. However decadal rainfall in the country had shown a slight decrease in rainfall.
Releasing the forecast for the Southwest Monsoon, the weather office said: "Forecast suggests that monsoon rainfall during monsoon season (June-September), 2022 averaged over the country as a whole is likely to be normal (96-104% of LPA)."
The monsoon in the country as a whole is likely to range be normal with above normal seasonal rainfall most likely over many areas of the northern peninsula and central India, along foothills of the Himalayas and some parts of northwest India. Below normal rainfall is likely over many parts of Northeast India, some parts of northwest India and southern parts of the South Peninsula.
"There is a slight decrease in rainfall but it's because of negative epoch and part of decadal variability of the Indian summer monsoon. There is climate change as the number of days of heavy rainfall is increasing and of normal and longer rainfall is decreasing," said IMD Director General M Mohapatra.
According to the weather office, the new All-India rainfall normal based on data from 1971 to 2020 for the southwest monsoon season (June- September) is 868.6 mm. It will replace the normal of 880.6mm based on data from 1961 to 2010.
The New All-India annual rainfall normal based on data from 1971 to 2020 is 1160.1 mm compared to the earlier normal of 1176.9 mm (based on data from 1961 to 2010).
"This decrease is part of natural multidecadal epochal variability of dry and wet epochs of all India rainfall. Presently it is in a dry epoch that started between 1971-80. The decadal average of all India SW monsoon rainfall for the decade 2011-20 is -3.8% from the long-term mean. The next decade i.e. 2021-30 will come closer to normal and likely to enter into a wet epoch from the decade 2031-40," added Mohapatra.
New rainfall normal has been computed using rainfall data from 4132 rain gauge stations well distributed over the country representing 703 districts of India.
South West Monsoon rainfall of India contributes 74.9% of Annual Rainfall. June, July, August, and September contribute 19.1%, 32.3%, 29.4% & 19.3% respectively to total SW monsoon rainfall.
All India Premonsoon rainfall (130.6mm) is around 11% of annual rainfall and while northeast monsoon contributes around 10% to the annual rainfall of India.