NEW DELHI: Southwest (summer) monsoon set in over Kerala on Thursday, three days after its normal onset date, India Meteorological Department (IMD) said. Monsoon normally sets in over Kerala on June 1, marking the beginning of four-month rainy season as well as Kharif sowing operations in India.It is only the second time in the past 22 years (2005-26) when the IMD’s operational forecast of the onset date over Kerala was off the mark as the Met department had earlier predicted May 26 as this year’s monsoon onset date, with a model error of +/- 4 days. The first time when its prediction proved to be wrong was in 2015.
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IMD has been issuing operational forecasts for the date of Monsoon onset over Kerala from 2005 onwards, using an indigenously developed statistical model with a model error of ± 4 days.Last year, monsoon arrived over Kerala on May 24, eight days in advance. Early or late arrival of monsoon has nothing to do with the overall quantitative or spatial rainfall during the rainy season. Delay in its progress over different states, however, impacts sowing of paddy, maize, pulses and other Kharif (summer sown) crops. Progress of the monsoon and its overall status depends on multiple climatic factors. Amid the growing risk of El Niño, the IMD has already predicted ‘below normal’ monsoon rainfall this year with 60% probability of its being ‘deficient’, triggering a fear of drought if it reports more than 10% deficit in overall quantitative rainfall during June-Sept period.Incidentally, the year 2015 when the IMD’s forecast of monsoon onset date turned wrong was also the drought year with a 14% deficit in the overall seasonal rainfall.
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“The southwest monsoon has further advanced into remaining parts of southwest and southeast Arabian Sea… entire Lakshadweep islands, Kerala and Mahe; some parts of Karnataka and Tamil Nadu; remaining parts of Comorin area; southeast Bay of Bengal… on June 4,” said the IMD while announcing the monsoon onset over India’s mainland.Making forecast of its further progress, it said, “Conditions are favourable for further advance of southwest monsoon into some more parts of central Arabian Sea, entire Goa, some parts of Maharashtra and Andhra Pradesh, some more parts of Karnataka, remaining parts of Tamil Nadu… and some parts of northeastern states during the next 2-3 days.”
