The India Meteorological Department (IMD) on Saturday said conditions are still not right to declare onset of monsoon over Kerala.

The IMD’s reaction came after the private forecaster Skymet Weather announced that the southwest monsoon has arrived in Kerala before its onset schedule. After this, in a tweet Ministry of Earth Sciences secretary Madhavan Rajeevan said the news about monsoon onset over Kerala in social media is not correct. Monsoon has not arrived over Kerala. The IMD also issued a twin depression alert for the Arabian Sea as the latter readies to match the Bay of Bengal in terms of the build-up for a spectacular onset of the monsoon over Kerala. The monsoon had hitched a hike on an eventual super cyclone Amphan to enter the Bay almost 10 days ago.

According to the IMD director general Mrutunjay Mohapatra, conditions are still not right to declare onset of monsoon over Kerala.” Conditions are becoming favourable for further advance of Southwest Monsoon into some more parts of south Arabian Sea, Maldives-Comorin area, southwest and the southeast Bay of Bengal during next 48 hours,” the IMD said.

According to the IMD, there are three major conditions to declare the onset of monsoon. The first is if, after May 10, 60 per cent of the 14 weather stations -- Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kudulu and Mangalore - report rainfall of 2.5 millimetres or more for two consecutive days, the onset over Kerala will be declared on the second day. The second is the depth of westerlies should be maintained up to 600 hectopascals (hPa) and the third is the Out wave Longwave Radiation should be below 200 watt per square metre (wm-2).

The IMD said that twin depression has been tracked over south coastal Oman and adjoining Yemen. It is very likely to intensify further into a deep depression during next 12 hours. It is very likely to move slowly west-northwestwards during next 12 hours and west-southwestwards thereafter. “Another low pressure area is very likely to form over southeast & adjoining east central Arabian Sea during next 48 hours. It is very likely to move north-northwestwards and concentrate into a depression over east central and adjoining southeast Arabian Sea during subsequent 48 hours,” it said.

Earlier, Skymet Weather CEO Jatin Singh said all conditions such as rainfall, Out wave Longwave Radiation (OLR) value and wind speed have been met to declare the arrival of the southwest monsoon over Kerala.

“#JUSTIN Southwest #Monsoon2020 finally arrived on the mainland of India, #Monsoon arrived on Kerala before the actual onset date. All the onset conditions including rainfall, OLR value, wind speed, are met. Finally, the 4-month long festival begins for Indian. #HappyMonsoon (sic),” the private forecaster tweeted. The onset of monsoon over Kerala marks the commencement of four-month rainy season in the country. The country receives 75 per cent of the rainfall from June to September. 

Skymet had predicted that monsoon will hit Kerala on May 28 with an error margin of plus or minus 2 days. Whereas, the India Meteorological Department (IMD) had said the monsoon will make an onset over Kerala on June 5, four days after its normal onset date. However, earlier this week, it said a cyclonic circulation in the Bay of Bengal will help in advancement of the monsoon and it could reach Kerala on June 1, its normal onset date.