INCOIS High Wave Forecasts (Kallakkadal) Support Timely Disaster Preparedness and Evacuation Along Kerala Coast

The Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, successfully forecast a high-amplitude swell wave (Kallakkadal) event affecting the Kerala, South Tamil Nadu and Lakshadweep coasts during 19–20 August 2026. The early warning, including a red alert for vulnerable coastal areas, provided critical lead time to the Kerala State Disaster Management Authority (KSDMA) and District Disaster Management Authorities (DDMAs) to disseminate alerts and implement precautionary measures. The forecast indicated high-energy, long-period swell waves with wave heights reaching up to 2.1 m and peak periods of around 21 seconds, originating from distant storms in the southern Indian Ocean. The forecast was subsequently supported by real-time observations from INCOIS wave-rider buoy platforms off Kozhikode, Kanyakumari, and Tuticorin. The timely warning enabled coordinated action and coastal restrictions, contributing to the safety of vulnerable coastal communities. The Government of Kerala formally conveyed its appreciation and gratitude to INCOIS for the successful forecast and continued guidance.

INCOIS provides operational forecasts of ocean conditions around India during extreme marine events such as high waves, swell conditions and cyclones. These forecasts are generated using multi-model numerical ocean prediction systems integrated with real-time observations from moored buoys, wave-rider buoys and other ocean observing platforms, including observations from the southern Indian Ocean. Kallakkadal is particularly challenging because high-energy long-period swells generated by distant weather systems can reach the coast even when local weather conditions remain relatively calm, with no nearby cyclone or other obvious extreme weather system. The resulting high waves can pose serious risks to fishing communities, small fishing crafts, coastal settlements, and low-lying areas.

For the 19–20 August 2026 event, INCOIS forecast the arrival of high-period swells propagating from the southern Indian Ocean towards the Indian coast. Swell heights of up to 2.1 m, with peak wave periods of approximately 21 seconds, were anticipated, with the long-period waves expected to interact with high-tide conditions and produce intermittent coastal flooding. The forecast provided valuable advance information to KSDMA and DDMAs, enabling timely dissemination of alerts and implementation of precautionary measures, including restrictions on small fishing crafts. A coordinated response involving the Navy, Coast Guard, Fisheries Department, Marine Enforcement, Coastal Police, Local Self Governments and Revenue Department was undertaken under the leadership of District Collectors. The occurrence of the high-period swells was subsequently confirmed through real-time observations from INCOIS wave-rider buoys deployed off Kozhikode, Kanyakumari,, and Tuticorin. KSDMA also documented the event through photographs and videos and shared the evidence with INCOIS for forecast validation. Recognizing the effectiveness of the warning and the continuous scientific guidance provided by the INCOIS team, the Government of Kerala formally placed on record its appreciation and gratitude to INCOIS. The successful event demonstrates the critical role of operational ocean forecasting in protecting coastal communities from hazards that can develop even under otherwise normal weather conditions.

Contribution from Indian Seas Regional Team

Useful links:

Learn more about the work of INCOIS here:  INCOIS | Indian National Centre for Ocean Information Services

Learn more about the Indian Seas Regional Team here: Regional Team: Indian Seas | OceanPrediction DCC

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