Average rainfall hides weather extremes: report

  1. A report titled ‘The Face of Disasters 2019’, published by Sustainable Environment and Ecological Development Society (SEEDS) has noted that IMD’s normal monsoon prediction gives only a myopic view. It does not give insights on extremes of floods and droughts across India.
  2. Recently, the India Meteorological Department (IMD) has said monsoon rains are expected to be normal in 2019. ‘Normal’ rainfall is defined as 96%-104% of the long period average (LPA), with a model error of plus or minus 5%. The LPA is the weighted average of rainfall that India received in June-September from 1951 to 2000 and is pegged at 89 cm.
  3. The IMD issues two long-range forecasts for the southwest monsoon. The first stage forecast is issued in April and the second stage in early June. The second stage forecast covers the four homogenous regions of the country viz. Central India, Peninsular India, Eastern India and North-western India. IMD provides monthly monsoon rainfall forecast for the months from June to September.
  4. However, the forecast does not provide a comprehensive picture. For example, in 2018 monsoon season, Punjab had experienced a “normal” monsoon with rainfall just 7% higher than the average rainfall in the State. However, that figure ignored the fact that Ropar had 71% excess rainfall while Ferozepur district experienced a 74% shortage.