NEW DELHI: The southwest (summer) monsoon has set in over Kerala on Thursday, three days after its normal date, IMD said. Monsoon normally sets in over Kerala on June 1, marking the beginning of rainy season as well as sowing operations in India.Last year, monsoon arrived over Kerala eight days in advance on May 24. Early or late arrival of monsoon has, however, nothing to do with the overall quantitative or spatial rainfall during the four-month rainy season. Overall status of the monsoon and its advancement depend on multiple climatic factor.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.

“The southwest monsoon has further advanced into remaining parts of southwest and southeast Arabian Sea, some parts of westcentral and east-central Arabian Sea, entire Lakshadweep islands, Kerala and Mahe, some parts of Karnataka and Tamil Nadu, remaining parts of Comorin area, southeast Bay of Bengal and some more parts of southwest, westcentral, eastcentral and northeast Bay of Bengal on June 4,” said the IMD while announcing the monsoon onset over India’s mainland.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, Southwest Bay of Bengal, some more parts of Westcentral, Eastcentral and Northeast Bay of Bengal, some parts of Northeastern states during the next 2-3 days.”IMD had earlier predicted May 26 (with a model error of +/- 4 days) as the monsoon arrival date over Kerala. The forecast, made on May 15, however, went off the mark.The Met department has been issuing operational forecasts for the date of Monsoon onset over Kerala from 2005 onwards. An indigenously developed state of the art statistical model with a model error of ± 4 days is used for the purpose.