The Regional Meteorological Centre (RMC) has forecast heavy rainfall in Chennai and the adjoining districts of Kancheepuram, Tiruvallur, and Chengalpattu on Wednesday.
Heavy rains are also expected in Cuddalore and Villupuram districts&nbsp;through the day.
Moderate rainfall is predicted in Mayiladuthurai, Nagapattinam, Virudhunagar, and Karaikal areas.
Light to moderate rain may occur in many parts of the state, especially in North Coastal Tamil Nadu, while a few areas across the rest of the state will also experience showers.
Puducherry and Karaikal are also likely to receive similar rainfall, with thunderstorms and lightning possible in isolated places.
The rains are attributed to a low-pressure system forming over the southeast Bay of Bengal, influenced by an upper-air cyclonic circulation over the South Andaman Sea and nearby areas.
This system is expected to intensify and move west-northwest towards the Tamil Nadu coast on December 18.
Heavy rains are likely in isolated places across Chennai, Tiruvallur, Chengalpattu, Kancheepuram, Ranipet, Tiruvannamalai, Kallakurichi, Mayiladuthurai, Nagapattinam, and Tiruvarur districts, as well as Karaikal.
There is a possibility of extreme rains between Marakkanam and Sriharikota due to interactions of westerly and easterly winds near south coastal Andhra Pradesh or north coastal Tamil Nadu.
The stretch from Pondicherry to Nellore may also witness heavy to very heavy rainfall. Tamil Nadu has received 14% excess rainfall during the ongoing northeast monsoon season, recording 447mm against an average of 393mm.
Chennai registered 845mm of rainfall, which is 16% above average, while Coimbatore saw a 47% increase.
Fishermen have been advised to avoid venturing into the sea.&nbsp;Those already at sea have been urged to return to shore immediately.
The current alert follows the devastation caused by Cyclone Fengal between November 29 and December 1, which brought intense rains and widespread damage.
The cyclone led to a loss of 12 people, 2,11,139 hectares of land getting inundated, affecting crops significantly even as 1,649km of electric conductors were destroyed, 23,664 electric poles, 997 transformers, 9,576km of roads, 1,847 culverts and 417 tanks were also destroyed.
Notably, Villupuram, Tiruvannamalai, and Kallakurichi districts recorded over 50cm of rainfall in a single day, equivalent to an entire season&rsquo;s average. The disaster resulted in severe flooding, extensive crop damage, affected 69 lakh families and 1.5 crore individuals across the state.
Chief Minister MK Stalin has requested ₹2,000 crore as interim relief from the National Disaster Response Fund.
The Tamil Nadu government&rsquo;s initial damage assessment report estimated relief and reconstruction costs at ₹2,475 crore.
The Central government has sanctioned ₹944 crore as interim relief.
&mdash;IANS

A view of a Chennai beach lashed by waves and heavy rain ahead of Cyclone Fengal's landfall

Low-pressure system forming over the southeast Bay of Bengal expected to intensify

Chennai, Adjoining Districts to See Heavy Rain

Low-pressure system forming over the southeast Bay of Bengal expected to intensify

December 18, 2024 | 09:03 IST