KOCHI: ClOSE on the heels of the India Meteorological Department (IMD) forecasting a normal monsoon this year, a debate is raging among meteorologists on the possibility of Kerala facing a third consecutive year of catastrophic flooding. Independent weather forecaster Pradeep John, popularly known as the Tamil Nadu Weatherman, had indicated in a Facebook post the possibility of Kerala facing an intense rainfall for a third consecutive year. However, meteorologists in Kerala have disputed his argument, pointing out that the intensity of the downpour cannot be predicted in advance.
Though the possibility of the state receiving over 2,300 mm rainfall cannot be ruled out, it may not translate into a flood, especially if it is spread over four months, said experts. “It was a short spell of intense rainfall, comparable to a cloudburst, that triggered the floods in 2018 and 2019. The state received 758.6mm rainfall between August 1 and 19 in 2018, which was 164 per cent above normal.
Similarly, it was a week-long intense rainfall from August 1 to 7 in 2019 that triggered the massive landslides at Kavalappara and Puthumala in Nilambur. The area received 550mm rainfall over a period of three days,” said S Abhilash, assistant professor, Department of Atmospheric Sciences, Cusat.‘A hat-trick has happened before’Though the Tamil Nadu Weatherman did not forecast a flood, his analysis has triggered speculations that the state was bracing for yet another devastating flood. “Kerala had recorded a hat-trick of heavy downpour in 1922, 1923 and 1924.
The state witnessed intense rainfall of 2,517mm in 2018 and 2,310mm in 2019. I won’t be surprised if Kerala records over 2,300mm rainfall for the present year as well, based on the past statistics,” he wrote on his Facebook page. “In the past 120 years, Kerala has received over 2,300mm rainfall as many as 27 times during the Southwest Monsoon. If this rainfall is distributed across the four months from June to September, it may not lead to flooding. Among these 27 years, 1924 tops the list with 3,451mm (+69 per cent) rainfall. The 2018 rainfall stands at the twelfth position with 2,515mm (+23 per cent), while the 2019 rainfall stands at the 26th position with 2,309mm (+13 per cent). The rainfall in Kerala has exceeded the 2,300mm threshold only four times after 2000 (2007, 2013, 2018 and 2019),” said Abhilash.
Supporting Abhilash’s argument, former IMD chairman S Sudevan said it was difficult to predict rainfall and flood two months in advance.“The IMD forecasted normal rainfall by dividing the country as four zones and analysing the conditions in these areas. There is a chance of one division receiving heavy downpour. Cyclones or depression can change the climatic conditions,” he said.“Forecasts can be made only 10 to 15 days in advance. We cannot predict anything now. All we can do is prepare a dynamic model and monitor the situation qualitatively,” said Sudevan.
IMD prediction
There is a high probability (70 per cent) of 2020 monsoon rainfall being above normal to excess (more than 104 per cent of long period average (LPA) — the average of rainfall received over a 50-year period from 1951 to 2000)