Southwest Monsoon status has been classified into 5 grades. The long period average (LPA) rainfall has a base of 50 years and is normally revised every 10 years. The oldest decade gets excluded and the recent one finds inclusion in the 50 years database. The current LPA of monsoon season is 868.6mm, based on data period 1971-2020. The seasonal rainfall varies from ‘Drought’ to ‘Excess’. Seasonal rainfall between June to September is graded as per the actuals during this period.
Incidents of drought and excess are normally within 10% of the occasions, albeit with exceptions in some of the monsoon cycles. About 50% cases fall in the normal category and the rest of 40% gets shared equitably between below normal and above normal. Monsoon over the Indian Sub-Continent has a cyclic pattern. Between 1921 and 1940, there was no drought for 20 years. Similarly, the period from 1952 – 1964 also remained drought-free. In the recent past, there was no drought for 14 years between 1988 and 2001. However, 21st century has seen a spate of droughts. Year 2002, 2004, 2009, 2014 and 2015 raised the proportion of droughts exponentially. Even, 2018 also missed it narrowly and the season ended with a deficit of 9.4%.
Season 2022 is expected to be ‘normal’. If so, this will be 4th season in a row to end with normal or above normal. Before this, 2019 and 2020 performed well to get listed in ‘above normal’ with 110% and 109% of LPA respectively. Last year, 2021 finished with 99% of LPA, registering a hat- trick of good monsoon. Earlier also, there have been some occasions, of achieving such fetes.
Courtesy La Nina conditions in the Pacific Ocean, Indian monsoon is likely to bring cheers for the farming community for 4th year in a row. These conditions are expected to persist with more than 60% chance during 1st half of the season and drop marginally during the later half. However, Indian Ocean is not promising any prolific season. A -ve IOD event is likely to build up, more strongly during the 2nd half of the season. Monsoon will have to ride over La Nina, battling IOD which is likely to drop below the threshold value from June to September.
