The Southwest Monsoon, according to private weather forecasting agency Skymet, has hit Kerala on Monday, marking the arrival of the rainy season in the country. The Indian Meteorological Department (IMD), however, in its 8.15 am bulletin, said monsoon would reach Kerala in the next 24 hours, on May 29.
“There are Monsoon-like conditions over Kerala and we can say that the annual rainfall season has arrived,” quoted Skymet CEO Jatin Singh as saying.
IMD’s main parameter to decide the arrival of monsoon is by measuring the rainfall in its available 14 stations. If 60 per cent of the available 14 stations — Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kudulu and Mangalore — report rainfall of 2.5 mm or more for two consecutive days after May 10, the onset of Monsoon over Kerala can be declared on the second day.
The other criteria, based on which the IMD decides whether Monsoon has arrived, is by measuring the westerly winds, which must be up to 15,000 feet above main sea level and the outgoing long-wave radiation should be less than 200 wm-2 (watt per square metre).
“The long-wave radiation is 140 wm-2. Rain for consecutive two days have been recorded in almost all weather stations and even the wind criteria has matched to safely say that the Monsoon has hit Kerela,” Mahesh Palwat, Vice-President (Meteorology and Climate Change) of Skymet told media.
The IMD forecast said that the Southwest Monsoon will find favourable conditions for advancing further into certain parts of South Arabian Sea, remaining parts of Comorin Maldives area, some parts of Kerala, Tamil Nadu, some more parts of South Bay of Bengal, remaining parts of Andaman Sea and Andaman and Nicobar Islands during the next 24 hours.
“The Monsoon is expected to hit Kerala in the next 24 hours,” Mritunjay Mohapatra, Additional Director General, IMD said.