Active Monsoon Over South Peninsula: Heavy Rains Likely

Key Takeaways:

• The Northeast Monsoon has commenced over South India with heavy rainfall, including 127 mm at Paramathy in Tamil Nadu.
• Widespread heavy rain with isolated very heavy spells is likely across Tamil Nadu, Kerala and Karnataka over the next 3–4 days.
• A cyclonic circulation extending up to 18,000 feet is supporting active rainfall conditions across the southern peninsula.
• Rainfall may continue for another 4–5 days before gradually weakening, with a possible break during the last week of October.
• Forecast Validity: Next 4–5 days.

The Northeast Monsoon made its onset yesterday over the South Peninsula and lashed many parts with heavy rains. Paramathy and Coimbatore in Tamil Nadu received 127 mm and 62 mm of rainfall, respectively. Karaikal, on the coastline, recorded heavy showers of 56 mm for the second consecutive day. Deep inland, Tirupati registered 50 mm of rainfall, and Kannur in Kerala was lashed with 58 mm during the overnight activity. Moderate showers have been observed across all five sub-divisions of the Northeast Monsoon. More rains are likely in the next 3–4 days.

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There is a cyclonic circulation marked over the interiors of the South Peninsula, covering parts of Tamil Nadu, Rayalaseema, South Interior Karnataka and Kerala. The circulation extends up to 18,000 feet, shifting eastward with height along the Kerala Coast. The system has a north-south trough extending from the southern tip of the peninsula to North Interior Karnataka. This feature is likely to remain over the same area with minor east-west oscillations before shifting eastward across the coastline into the Arabian Sea.

Widespread heavy rainfall, with very heavy falls at isolated places, is likely over the southern states, predominantly below 15°N. The places at risk will include Trichy, Madurai, Thanjavur, Coimbatore, Tirupur, Salem, Erode, Ooty and Kodaikanal in Tamil Nadu. Similar weather conditions are expected over many locations in Kerala and Karnataka. The vulnerable places will include Kannur, Palakkad, Malappuram, Idukki, Wayanad, Kochi, Kottayam and Thrissur in Kerala. The susceptible locations for inclement weather conditions in Karnataka will be Bengaluru, Mysore, Mandya, Hassan, Chamarajanagar and Chitradurga.

As the weather system moves across the coastline to enter the Arabian Sea, the intensity and spread may ease out a bit. However, rainfall will continue for the subsequent 4–5 days, more significantly over the left half and extreme southern parts of the South Peninsula. These rains are likely to slow down and may even take a break in the last week of October.