Cyclone Mocha, brewing in the Bay of Bengal, will herald the return of peak summer heat, popularly called ‘Agninakshatram’, over Tamil Nadu.
Most parts of the State may have to brace for scorching heat as rainfall and balmy weather may ease up. On Wednesday, some weather stations felt the heat. Karur Paramathi recorded 38 degrees Celsius; Vellore (37.7 degrees Celsius) and Tiruttani (37.1 degrees Celsius). In Chennai, Nungambakkam and Meenambakkam registered 36.8 degrees Celsius and 37.5 degrees Celsius respectively. Only Tirunelveli and Thoothukudi received light rain till 5.30 p.m. on Wednesday.
The weather system may put an end to the below average temperature and the rain that many districts enjoyed during the early May.
The India Meteorological Department has forecast a gradual rise in the mercury level by two-four degrees Celsius in the State till May 14. It has also warned that soaring maximum temperature, coupled with high humidity, may cause discomfort to some citizens.
The cyclone would be the cause for the drastic drop in rainfall and return of heat wave in the State. According to IMD, the system would become a severe cyclonic storm by Thursday and further intensify as a very severe cyclonic storm by midnight Thursday over the south-east and central Bay of Bengal. It is likely to recurve, move north-northeastwards and cross the south-east Bangladesh and north Myanmar coasts around May 14.
S. Balachandran, Additional Director-General of Meteorology, Chennai, said the Bay of Bengal would whip up pre-monsoon disturbances as strong as severe cyclonic storms. However, 80%-90% of them would re-curve and travel to other parts like West Bengal or Myanmar. Fishermen have been warned not to venture into sea.
Cyclone Mocha would cause dry, hot westerly winds to sweep over the State and inflate the temperature. Convective activity might trigger thunderstorms in interior areas till May 14. Pointing to Cyclone Roanu, which came close to the Tamil Nadu coast in May 2016, he noted that the pre-monsoon systems had rarely touched the Tamil Nadu coast.
Chennai would experience a maximum temperature of 36-37 degrees Celsius till Friday, and light rain in some areas.
Y.E.A. Raj, former Deputy Director-General of Meteorology, Chennai, said 29 weather disturbances formed in the Bay of Bengal during May between 1981 and 2021.
Of them, 15 were severe cyclonic storms and five were cyclonic storms. A majority of them had recurved north and northeastwards and mostly made landfall in other places like Odisha, Bangladesh and West Bengal.
Pre-monsoon cyclones were common during May, he said, and the case in point was a weak depression in May 1995 that crossed the coast near Cuddalore.