Chennai is set to experience heavy to very heavy rainfall as the Cyclone Nivar is expected to make landfall between Mamallapuram and Karaikal by Wednesday noon or afternoon.

Rainfall of 6cm to 10cm is expected, said a report in the Times of India. As the weather system is too far away, Monday will be mostly cloudy with light drizzle. It will start raining on Tuesday as the cyclone draws nearer to the coast. When it starts to make landfall on Wednesday, Villupuram, Cuddalore, Puducherry and Chennai are forecast to have heavy rain.

The Indian Meteorological Department (IMD) said in the next 12 hours, a well-marked low pressure in the Bay of Bengal closer to the Tamil Nadu coast will intensify into a depression, and will develop into a cyclonic storm in the next 24 hours, moving at 18kmph speed towards the coast.

Deputy Director of the regional meteorological centre in Chennai S Balachandran said rain would start in coastal districts on Monday and intensify step-by-step, adding that on Tuesday and Wednesday, some areas on the coast would get heavy rain and very heavy rain.

Warning fishermen to not venture into the sea till November 25, Balachandran said there were chances of heavy rain to start in the city and its suburbs on Tuesday.

The well-marked low pressure is located 700 km from Karaikal and 760km away from Chennai and it will skirt the coast of Sri Lanka, and move northwest to brace the Tamil Nadu coast.

Named cyclone Nivar by Iran, it is moving at a good speed, said a met official. The low pressure is quickly turning into a depression, in 12 hours instead of the 24 hours forecast earlier.

ALERT SOUNDED IN NAGAPATTINAM, KARAIKAL

As Cyclone Nivar heads toward the Tamil Nadu coast, the Nagapattinam district administration has advised fishermen to keep their boats safe to prevent damage, the New Indian Express reports.

All departments in Nagapattinam are on high alert, including finance, disaster management, police, forestry, health services, and rural development. All the fishermen were asked to return to the shore immediately.

Officials are also concerned that Cyclone Nivar could deviate slightly in its direction, like Cyclone Gaja, which could put at risk the southern half of the district of Nagapattinam.