Chennai, 20 October: The Regional Meteorological Centre (RMC) here has warned that an upper air cyclonic circulation over the southwest Bay of Bengal is likely to intensify into a low pressure area within 24 hours, increasing the risk of heavy rainfall across parts of Tamil Nadu and the Union territory of Puducherry.
Orange alert for very heavy rain in coastal and delta districts
In a bulletin issued on Tuesday at 1.40 pm, the RMC said heavy to very heavy rain is likely at isolated places over Chennai, Tiruvallur, Chengalpattu, Cuddalore, Villupuram, Thanjavur, Thiruvarur, Nagapattinam, Mayiladuthurai and Ramanathapuram, and in the Puducherry and Karaikal areas during the next 24 hours. The India Meteorological Department (IMD) has put these districts under an orange alert, a category that denotes the possibility of very heavy rainfall exceeding 11 cm in a 24-hour period.
The bulletin also cited a wider spread of heavy showers in several interior and southern districts, including Ranipet, Kancheepuram, Kallakurichi, Tiruchirappalli, Ariyalur, Perambalur, Pudukkottai, Sivagangai, Tenkasi, Tirunelveli and Kanyakumari.
Recent rainfall and recorded totals
Officials noted that the state recorded widespread rainfall during the 24-hour period starting Monday. While Chennai — which experienced intense downpours on Saturday night, with some low-lying areas such as Parrys receiving in excess of 30 cm — saw only moderate showers over the weekend, other parts of the State reported notable accumulations.
| Location | Recorded rainfall (last 24 hours) |
|---|---|
| Amaravathi Pudur (Sivagangai district) | 9.2 cm |
| Tiruvadanai (Ramanathapuram district) | 8 cm |
What the bulletin says
The RMC bulletin explained that an upper air cyclonic circulation lying over the southwest Bay of Bengal off north Tamil Nadu on Monday is expected to intensify into a low pressure area over the same region during the next 24 hours. Such systems commonly enhance moisture convergence and instability over adjacent coastal and interior districts, increasing the likelihood of heavy spells.
- Timeframe: Next 24 hours from the 1.40 pm bulletin issued on Tuesday.
- Primary impact area: Chennai and several coastal and delta districts named in the bulletin.
- Alert level: Orange alert — indicating a forecast of very heavy rain (> 11 cm) at isolated places.
Local context and likely impacts
Residential localities, arterial roads and low-lying areas in coastal districts remain vulnerable to waterlogging and temporary disruption. The bulletin follows recent intense rainfall events in Chennai that left parts of the city inundated; authorities and residents across the state commonly prepare for such episodes by reviewing drainage clearance, traffic management and preparedness of relief agencies.
Official sources said that while Chennai recorded heavy precipitation on Saturday night, the city experienced only relatively moderate rain from Sunday onward. However, given the forecast for renewed heavy showers, urban agencies and emergency services will be closely monitoring the situation.
Advice for the public
The IMD advisory emphasises that residents should keep abreast of weather updates and heed instructions from local authorities. Basic precautions during heavy rainfall typically include avoiding unnecessary travel, steering clear of low-lying stretches known to flood, securing loose items outdoors and following directions from municipal and revenue officials.
Fishermen and those operating small vessels along the coast are usually advised to suspend operations during such systems; however, specific advisories for maritime operations will be issued by the relevant coastal authorities and port authorities if warranted.
State and district administration, municipal corporations and disaster-response agencies often activate contingency plans during orange and red alerts. Citizens are advised to follow bulletins from the RMC and local disaster management offices for minute-to-minute information.
Further updates will be issued by the Regional Meteorological Centre as the low pressure area evolves and its track becomes clearer.
Selvan Murugesan reports from Chennai.
