Tamil Nadu coast may have to contend with the next ‘low’ in a week’s time

India Met Department has joined global models in their look-out for an increase in rainfall over South Peninsular India from the weekend.

Global models suspect that the North Tamil Nadu-South Coastal Andhra Pradesh coasts are bracing to receive flooding rains from a likely low-pressure area/depression in another week’s time (by December 1).

Rain-bearing clouds are expected to head from the Andaman and Nicobar Islands towards the Tamil Nadu and Puducherry coasts by Wednesday/Thursday.

In fact, the Met has already predicted that heavy rain would lash the islands in the extreme South-East Bay of Bengal from Wednesday.

Already, a trough (lesser in grade than a low-pressure area) exists in the South-West Bay of Bengal off the Sri Lanka and Tamil Nadu coasts, which may hasten the process of formation of the ‘low.’

The US Climate Prediction Centre has maintained an ‘excess rainfall’ watch over the North coast of Tamil Nadu (around Chennai) and the entire East of Sri Lanka right until December 5.

The European Centre for Medium-Range Weather Forecasts builds a better perspective by linking the fresh wave of rains to a typhoon in the Northwest Pacific.

Typhoon In-Fa has been moving in a typical West-Northwest direction East of the Philippines over the last few days and is now forecast to turn North-Northeast towards Japan (away from South Asia).

But In-Fa is forecast to send in a remnant circulation into South China Sea, which would move further West across the Gulf of Thailand and into the Andaman Sea by Thursday/Friday.

This remnant is expected to set up a low-pressure area in the Andaman Sea, which could intensify a round as a likely depression as it negotiates the waters towards India’s East Coast.

The system is forecast to meander initially towards the Tamil Nadu coast, and end up in a landfall over Coastal Andhra Pradesh, North of Chennai, over by Tuesday (December 1).

This is likely to bring flooding rain to the entire Tamil Nadu coast as well as South Coastal Andhra Pradesh, as per earliest available forecasts.

India Met Department has put out the rain watch valid from tomorrow (Tuesday) as follows:

Tuesday: Thunderstorm with hail and lightning at isolated places over Madhya Maharashtra and Marathawada (thanks to the presence of trough that links them with a prevailing ‘low’ in Arabian Sea).

Wednesday: Heavy rain at isolated places over Nicobar Islands. Thunderstorms with hail and lightning in isolated places over Madhya Maharashtra.

Thursday: Heavy rain at isolated places over Nicobar Islands.

Friday: Heavy rain at isolated places over Coastal Tamil Nadu.