IMD predicts normal monsoon rainfall in 2022, new long-term normal figure shows marginal decline in rainfall in India | India News

NEW DELHI: Sending positive signals to India’s farm sector, the India Meteorological Department (IMD) on Thursday predicted ‘normal’ and fairly well-distributed monsoon rainfall for most parts of the country during the June-September period.
It said quantitatively, the southwest (summer) monsoon rainfall is likely to be 99% of the Long Period Average (LPA) with a model error of +/- 5%. Northeast India, some parts of northwest India and southern parts of the South Peninsula will, however, receive ‘below normal’ rainfall. But it’ll not affect the agriculture operations as the entire rainfed areas of the country will get normal to above rainfall.

The LPA of the seasonal rainfall over the country as a whole for the period 1971-2020 is 87 cm. The monsoon is considered normal if it falls under 96 to 104 % of LPA. The Met department predicted that there is 40% forecast probability of ‘normal’ rainfall, 15% probability of ‘above normal’ and 5% probability of ‘excess’ rainfall – which means there is 60% probability of good rainfall in the country during the summer season (June-September).
The spatial distribution suggests normal to above normal seasonal rainfall is most likely over many areas of northern parts of Peninsular India and adjoining Central India, over foothills of the Himalayas and some parts of Northwest India.

The IMD this year introduced a new rainfall normal figure based on 1971-2020 data, showing a marginal decline in monsoon rainfall and overall annual rainfall in the country over the long period. It attributed the decline in rainfall to climate change.
Under the new normal figure, All-India rainfall for the southwest (summer) monsoon is 87 cm as against the earlier normal figure of 88 cm based on the 1961-2010 period. New rainfall normal has been computed using rainfall data of 4132 rain gauge stations well distributed over the country, representing 703 districts.

The new All-India rainfall normal computed based on data of 1971-2020 for the southwest monsoon season (June-September) is 868.6mm (87cm). It will replace the earlier normal of 880.6 mm (88 cm) based on data from 1961 to 2010. The new All-India annual rainfall normal based on data of 1971-2020 is 1160.1 mm compared to the earlier normal of 1176.9mm based on data of 1961-2010.
Thus there is a decrease of 12.0 mm in mean rainfall during the southwest monsoon season and 16.8 mm in annual rainfall for the country as a whole from 1961- 2010 to 1971-2020.

“The decrease is part of natural multidecadal epochal variability of dry and wet epochs of all India rainfall. Presently, the southwest monsoon is passing through a dry epoch that started in the decade of 1971-80. The decadal average of all India SW monsoon rainfall for the decade 2011-20 is -3.8% of the long-term mean. The next decade i.e. 2021-30 is expected to come closer to neutral and southwest monsoon would enter into the wet epoch from the decade 2031-40,” said the IMD chief M Mohapatra while releasing the first forecast of the summer monsoon. He did not rule out the possibility of the impact of climate change on the decline in rainfall over a longer period of time.
The IMD will issue the updated forecasts for monsoon season rainfall in the last week of May. In addition to updates for the April forecast, forecasts for monsoon season (June-September) rainfall for four geographical regions, monsoon core zone, and forecast for the month of June will also be issued.