The Southwest monsoon has set in over Kerala on Sunday, three days ahead of the normal onset of June 1.
The India Meteorological Department (IMD) announced the arrival of the monsoon after the conditions set for declaration of onset of monsoon over Kerala are satisfied in the morning. There had been widespread rainfall activity over Kerala during the past 24 hours and out of 14 rainfall monitoring stations for declaring the onset of monsoon over Kerala, 10 stations had received rainfall of 2.5 mm or more, said an IMD bulletin.
Further, the strength of the westerly winds, another parameter, have increased over southeast Arabian Sea. Finally, cloudiness over southeast Arabian Sea and adjoining areas of Kerala have also increased, a parameter called outgoing longwave radiation (OLR) which is about 189.7 W/M2 (below 200 W/square metre).
Conditions are also favourable for further advance of southwest monsoon into some parts of central Arabian Sea, remaining parts of Kerala, some more parts of Tamil Nadu, Karnataka, and south and Central Bay of Bengal, northeast Bay of Bengal and northeastern States during the next three-four days, said the bulletin.
Announcing the arrival of monsoon, the IMD said the monsoon had advanced into the remaining parts of south Arabian Sea, Lakshadweep area, most parts of Kerala, some part of south Tamil Nadu, Gulf of Mannar and southwest Bay of Bengal on Sunday.
Under the influence of monsoon westerly winds from Arabian Sea over the south peninsular India in lower and middle tropospheric levels and a cyclonic circulation over Kerala and neighbourhood in mid tropospheric levels, the State is likely to receive widespread isolated heavy rainfall for the next four days. A yellow alert has been sounded in nine districts – from Thiruvananthapuram to Palakkad - warning of isolated heavy rain on Monday.
Squally weather with wind speed 40-50 kmph gusting to 60 kmp/h is very likely over southwest Arabian Sea during the next five days; over Southeast Arabian Sea, Lakshadweep area, along and off Kerala coast, Comorin area, Northeast Arabian Sea and adjoining Gujarat coast Monday.
Fishermen are advised not to venture into these areas. In the last 10 years, the onset of southwest monsoon in Kerala three days ahead of its normal date, was in 2018. The State has also received 98% excess pre-monsoon rainfall this year with the State netting 64.56 cm rain against the average of 32.62 cm.
Earlier, the IMD had forecast that the monsoon would arrive in Kerala on May 27 with an error margin of four days. The extended forecast issued by the IMD said the rainfall would be normal in the first week and below normal in Kerala in the second week.
