A low pressure area over south Andaman Sea and adjoining Bay of Bengal was "very likely" to concentrate into a depression in the next 48 hours and intensify further before moving towards the Tamil Nadu coast, the India Meteorological Department (IMD) said on Saturday.
Under its influence, various parts in southern states were likely to receive rainfall starting December 1, the IMD said in a series of tweets.
"A Low Pressure Area lies over South Andaman Sea adj SE (south east) Bay of Bengal and Equatorial Indian Ocean. It is very likely to concentrate into a depression during next 48 hours and likely to intensify further thereafter," it said.
It is likely to move nearly westwards and reach south Tamil Nadu coast around December 2, it said.
Under its influence, scattered to widespread rainfall activity was "very likely" over Tamil Nadu, Puducherry, Karaikal, Kerala, Mahe, Lakshadweep, south coastal Andhra Pradesh and south Rayalaseema on Tuesday and Wednesday, the weather office said.
IMD also forecast isolated heavy to very heavy rainfall with moderate thunderstorm and lightning over Tamil Nadu, Puducherry and Karaikal during this period.
Isolated heavy falls with moderate thunderstorm and lightning was also very likely over south coastal Andhra Pradesh during December 1 and 2 and over Rayalseema and Lakshadweep area on Wednesday, it added.