The National Centre for Ocean Information Services (INCOIS) has issued a red alert for all coastal districts of Kerala till August 20 due to high-energy swell waves approaching the Indian coast from the distant southern Indian Ocean. Waves ranging from 1.1 to 1.8 metres are expected, with low-lying coastal areas particularly vulnerable to flooding and sea incursions.

The phenomenon originated around 10,000 km from the Indian coast in the southern Indian Ocean on August 13 and has been gradually moving towards the northern Indian Ocean. The resulting high-energy swells, with a peak wave period of around 21 seconds, are expected to reach the southern tip of India in the early hours of Wednesday, with the impact likely to peak in the evening. Combined with high-tide conditions, the long-period swells could cause coastal flooding in low-lying areas of Kerala, southern Tamil Nadu and the Lakshadweep islands from 2.30 am on August 19 to 5.30 pm on August 20.

Fishermen and coastal residents in the affected areas have been advised to remain alert to intermittent surges of seawater in nearshore and beach areas, particularly in low-lying regions. Small vessels should not operate close to the shore, while boats should be anchored at a safe distance from one another to prevent collisions and damage. All operational and recreational activities, including tourism-related activities, at beaches and nearshore areas should be suspended until the warning is withdrawn.

The remaining coastal regions are under a swell surge alert, with low-lying areas particularly vulnerable. Special caution has been advised along the following stretches: Thiruvananthapuram – from Kappil to Pozhiyoor; Kollam – from Alappad to Edava; Alappuzha – from Chellanam to Azhikkal Jetty; Ernakulam – from Munambam FH to Maruvakkad; Thrissur – from Aattupuram to Kodungalloor; Malappuram – from Kadalundi Nagaram to Palappetty; Kozhikode – from Chombala FH to Ramanattukara; Kannur – from Valapattanam to New Mahe; and Kasaragod – from Kunjathur to Kottakkunnu.

A high-wave and Kallakkadal warning has also been issued for the coastal districts of Kanyakumari, Ramanathapuram, Thoothukudi and Tirunelveli in Tamil Nadu, as well as Lakshadweep, Mahe and the Karnataka coast.