Rare January Deep Depression Over Bay of Bengal to Bring Heavy Rainfall Across Parts of Tamil Nadu

A rare weather system over the Bay of Bengal has intensified into a deep depression, raising the likelihood of widespread rainfall across parts of Tamil Nadu over the next few days, meteorological officials said on Thursday.

The system, currently positioned over the southwest Bay of Bengal and adjoining equatorial waters, is expected to ease the prolonged dry spell in the State. Scattered rainfall, with heavy to very heavy showers in isolated areas, is forecast for coastal and delta districts for at least three days starting Friday.

According to the Regional Meteorological Centre, the deep depression lies several hundred kilometres southeast of Karaikal and south-southeast of Chennai. It is likely to cross the Sri Lanka coast between Hambantota and Kalmunai by Friday evening or night.

Weather experts noted that the formation of such an intense system in January is unusual. Historical records show that only about 20 intense weather systems have developed over the Bay of Bengal during January since 1891, making the current event a rare occurrence.

Orange and yellow weather alerts have been issued for several districts, warning of intense rainfall that could reach up to 20 cm in some locations. On Friday, heavy to very heavy rainfall is expected over districts such as Tiruvarur and Nagapattinam, while heavy rain may occur in Ramanathapuram, Pudukkottai, Mayiladuthurai and Thanjavur.

Rainfall activity is likely to expand further on Saturday, covering many coastal districts and parts of interior Tamil Nadu. The stretch between Chengalpattu and Ramanathapuram is expected to witness particularly intense showers, with isolated heavy rainfall possible in several districts. Meteorologists explained that most January weather systems over the Bay of Bengal are typically short-lived and rarely make landfall along the Tamil Nadu coast. Only a handful have intensified into cyclonic storms in the past six decades.

Meanwhile, ground frost conditions are likely to prevail over the higher elevations of the Nilgiris and Kodaikanal hills, highlighting the contrasting weather patterns expected across the State in the coming days.