NEW DELHI, May 30: Monsoon has set in simultaneously over Kerala and north-east on Thursday, a rare phenomenon witnessed last time in 2017, the India Meteorological Department said. The IMD had earlier forecast setting up of monsoon over Kerala on Friday.
Cyclone Remal, which formed in the Bay of Bengal, has led to India witnessing the rare phenomenon of monsoon setting in simultaneously over Kerala and most parts of the northeast. In 2017 too, Cyclone Mora had formed just before the monsoon that year, also over the Bay of Bengal.
The IMD said on Thursday that the Southwest Monsoon has set in over Kerala and also advanced into most of northeast India, including all of Nagaland, Manipur, Mizoram and Arunachal Pradesh, and most parts of Tripura, Meghalaya and Assam.
The monsoon usually arrives in Kerala on June 1 and in the northeast on June 5. From Kerala monsoon progress northwards in surges, and covers the entire country around July 15. All the criteria required for the declaration of the monsoon were met in the morning.
Rainfall over 2.5 mm was recorded over 14 stations in Kerala and neighbouring areas for two consecutive days, and the Outgoing Longwave Radiation (OLR) has been below 200 wm-2, a measurement that represents the amount of energy emitted by the earth’s surface and atmosphere into space.
Also, the depth of the westerly winds, which should be up to 600 hPa, indicating the strength of the monsoon winds, has also been satisfied. The average rainfall Kerala receives during the four-month southwest monsoon season is 2018.7 mm, while the opening month of June used to net around 648.3 mm of rainfall, the second largest monthly rainfall in the four-month season.
July has been the wettest month considering the 123-year monsoon data for Kerala, with an average rainfall of 653.4 mm. This year, the IMD forecasted an above normal rainfall for Kerala and the country as a whole. The likely development of La Nina during the first half of the monsoon season is expected to be beneficial for the Indian monsoon.
The IMD Director General Mryutanjaya Mohapatra said, “As of today, the southwest monsoon has reached Kerala and covered most parts of the state. It has also covered some parts of Tamil Nadu and also most parts of the north-eastern states.”
The IMD has predicted above-normal monsoon this year. The weather office defines average or normal rainfall as between 96 and 104% of a 50-year average of 87 cm for the June-September monsoon season. The monsoon accounts for over 70 per cent of India’s annual rainfall and plays a major role in the Indian economy as it is the only source of irrigation for nearly 50 per cent of the country’s farmland. Large swathes of the country also depend on it for the drinking water supply.
Delhi and other parts of the north, which are still reeling under record-high temperatures, will have to wait for the rain to reach them. The rains are expected to reach the national capital by the end of June.
On the heatwave, the IMD chief said, “The monsoon has set in over Kerala two days early and it will reach Mumbai on June 8. If we look at the weather pattern, the monsoonal features, I will say it is in very good condition for the continuance of this spell.”
(Manas Dasgupta)
