Decades-old official monsoon schedule likely to be reset soon

Vibha Sharma

Tribune News Service

New Delhi, July 21

With variations in the southwest monsoon pattern becoming increasingly visible, India appears to be preparing to reset the schedule it has been following since 1941. A committee looking into the issue is finalising the report and changes in the  June to September season may be effected as early as next year, said M Rajeevan, Secretary, Ministry of Earth Sciences, recently.

Head of IMD’s long-range weather forecast division in Pune DS Pai also spoke of  such changes. The rainy season is the key to the country’s entire economy. But significant changes have been seen in the monsoon pattern in the past 10 years. This year, for example, though its official arrival date was June 1, it hit the mainland in Kerala on June 8. Weak and tardy in the initial days, its further progress was slowed down by cyclones in the Bay of Bengal and Arabian Sea, further causing delay in the sowing of kharif crops across the country. It is not just the onset and withdrawal dates, quantity and distribution of rains have also seen variation in the past few years.

The IMD  admits while between 1988 and 2008, its forecasts were “qualitatively correct in 19 years (90% accuracy),” errors started creeping in later years. In 1994, 1997, 1999, 2002, 2004 and 2007,  the forecast error (difference between actual rainfall and forecast rainfall) was more than 10%, it says. “It’s not possible to have cent per cent success for forecasts based on statistical models, ” it adds.