High Wave Advisory for Open Seas
Overview
A high wave advisory for open seas is a weather warning issued by the Korea Meteorological Administration when wind speeds are expected to reach 14 m/s (approximately 27 knots) or higher, or significant wave heights are expected to be 3 m or more. Since this poses direct risks to ship navigation and fishing activities in broader sea areas than coastal zones, advance preparation and swift response are essential. Recently, due to climate change, the intensity of typhoons and low-pressure systems has increased, leading to a rising trend in the frequency and duration of high wave advisories.
Main Content
Definition and Criteria
A high wave advisory is issued when strong winds and high waves are expected at sea. Specifically, it is issued when wind speeds of 14 m/s or higher or significant wave heights of 3 m or more are expected. If stronger conditions—wind speeds of 21 m/s or higher or significant wave heights of 5 m or more—are anticipated, the advisory is upgraded to a high wave warning. Open seas refer to waters approximately 20–30 km or more from the coast, and predictions are based on marine weather observation buoys and satellite data.
Issuance Procedure and Dissemination
The Korea Meteorological Administration issues high wave warnings by comprehensively analyzing numerical weather prediction models and marine observation data. The issued warnings are rapidly disseminated through the KMA website, mobile apps, broadcasts, the Korea Coast Guard, and the Automatic Identification System (AIS) for ships. In particular, fishing vessels and large ships are required to be equipped with devices capable of receiving real-time marine weather information.
Impacts and Damage Cases
When a high wave advisory is issued, ship navigation is restricted and fishing activities are suspended. High waves can lead to ship capsizing, cargo loss, and human casualties. A notable case occurred in 2023 when three fishing boats capsized off the east coast due to high waves, resulting in five deaths. Additionally, in 2024, a high wave advisory persisted for five days on the west coast, causing damage to aquaculture facilities amounting to 10 billion won.
Preparedness and Response
Ships must evacuate to safe ports or cease navigation when a high wave advisory is issued. Fishermen should inspect aquaculture facilities and secure their vessels with moorings as preventive measures. The Korea Coast Guard strengthens port control and rescue readiness. The general public should avoid approaching the coast and refrain from fishing or leisure activities.
Latest Trends
As of 2024–2025, the frequency of high wave advisories has increased by approximately 20% compared to the 10-year average due to climate change. High waves have become more frequent in the East Sea and West Sea, particularly influenced by the northwest monsoon in winter and low-pressure systems in spring. The Korea Meteorological Administration has introduced an AI-based prediction model, improving the accuracy of high wave forecasts to 85%, and since 2025, it has been providing more detailed advisories on a three-hour basis. Furthermore, the Ministry of Oceans and Fisheries is expanding real-time marine observation systems using smart buoys and drones.
Related Topics
- [[Weather Warning]]
- [[Maritime Safety]]
- [[Climate Change]]
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