CHENNAI/NEW DELHI, 19 October 2025 — The India Meteorological Department (IMD) has issued warnings regarding the potential intensification of two simultaneous low-pressure weather systems developing over the Arabian Sea and the Bay of Bengal, a configuration that could significantly influence rainfall activity across southern India.
The severe weather has already caused immediate disruption, resulting in the cancellation of train services on the Nilgiri Mountain Railway due to heavy rains and multiple landslides reported on Sunday (October 19).
IMD Tracks Twin Threat
The complex weather pattern is setting the tone for an active phase of the northeast monsoon, which commenced earlier this week across Tamil Nadu and Kerala.
According to the latest IMD bulletins, twin developments are currently under observation:
- Bay of Bengal: A well-marked low-pressure area persists over the Kumarakom coast and the adjoining southwest Bay of Bengal. Further complicating the forecast, a fresh low-pressure area is likely to form over the southeast Bay of Bengal on October 24. This system is expected to move west-northwestward toward the Tamil Nadu coast, possibly intensifying as it approaches the mainland. By October 19, the IMD had warned that this developing system could gradually intensify into a deep depression.
- Arabian Sea: A cyclonic circulation has been observed over the southeast Arabian Sea and the Lakshadweep region in the upper atmospheric levels. This circulation is expected to spawn a new low-pressure system over the southeast Arabian Sea and Lakshadweep by Saturday night. Meteorologists predict this system will move west-northwestward and could intensify into a depression within 48 hours. The IMD also noted that another low-pressure area has already formed over the Arabian Sea, which is also likely to strengthen further over the next two days.
Landslides Halt Rail Travel
The relentless downpours have already caused substantial damage and travel halts. Train services on the Nilgiri Mountain Railway were cancelled on Sunday (October 19, 2025).
Southern Railway’s Salem Division reported multiple "earth slips" along the route between Kallar and Coonoor. These slips involved boulders, mud, and fallen trees obstructing the tracks. Services affected by the cancellations included Train No. 56136 Mettupalayam - Udagamandalam, Train No. 56137 Udagamandalam - Mettupalayam, and Train No. 06171 Mettupalayam - Udagamandalam Special Train.
Rainfall and Advisories
The weather office forecasted widespread light to moderate rain with thunderstorms and lightning over Tamil Nadu, Puducherry, and Karaikal.
Heavy rainfall was specifically expected at isolated places in numerous districts, including The Nilgiris, Coimbatore, Tiruppur, Theni, Dindigul, Erode, Salem, Namakkal, and Karur. Heavy rainfall in Thoothukudi resulted in waterlogging across parts of the district, prompting local authorities to declare a holiday for schools due to the severe conditions.
Advisories to Mariners and Residents:
Due to the complex and intensifying systems, extensive warnings have been issued:
- Fishermen have been advised not to venture into the southeast Arabian Sea and the adjoining Lakshadweep area due to rough sea conditions.
- Fishing advisories were issued along Tamil Nadu's shores, with the Assistant Director of the Department of Fisheries and Fishermen Welfare in Cuddalore District instructing all mechanized country boats, catamarans, and motorized fishing vessels not to venture into the sea until further notice. Fishermen currently in deep sea were instructed to return immediately.
- Coastal residents have been urged to remain alert for possible strong winds and localised flooding, especially in low-lying areas and river basins.
