A High Surf Advisory is a formal alert from weather agencies signaling that large ocean swells are expected to create dangerous surf conditions near the shore. Understanding these communication tools is important for public safety. Recognizing the meaning of this specific warning is the first step in avoiding potential harm when visiting the coast.
Defining the High Surf Advisory
A High Surf Advisory is issued by the National Weather Service (NWS) when breaking wave action is anticipated to pose a threat to life and property within the immediate surf zone. The criteria for issuing this advisory are locally defined to account for regional geography and typical wave climate. In many coastal regions, an advisory is triggered when sustained breaking waves are forecast to reach heights of eight feet or greater.
This alert is distinct from a more severe High Surf Warning, which signifies a heightened threat involving conditions that may cause widespread damage to coastal structures. An Advisory indicates hazardous conditions expected to impact those near the water, rather than threatening property integrity. These events are caused by distant storms or low-pressure systems that generate powerful, long-period swells. The conditions can persist for a few hours or extend over several days, requiring continuous monitoring of local forecasts.
Understanding Associated Coastal Hazards
The danger posed by high surf conditions stems from the increase in the waves’ physical energy as they break near the shore. The force of a wave increases exponentially with its height, meaning a wave only slightly taller than normal can be vastly more powerful. This increased energy generates stronger and more prevalent rip currents, which are narrow channels of water moving rapidly away from the shore.
High surf also intensifies longshore currents, which flow parallel to the coastline, making it difficult for a person to remain stable or swim against the flow. A particularly hazardous phenomenon is the occurrence of “sneaker waves.” These are unexpectedly large waves that travel far up the beach, catching people off guard even away from the waterline. This sudden rush of water can inundate beaches, wash people off exposed coastal features like jetties or rocks, and cause physical injury from the force of the surge.
Essential Safety Precautions and Actions
When a High Surf Advisory is in effect, the public should remain completely out of the water. Swimmers, surfers, and boaters should avoid all ocean entry, as the combined forces of large breaking waves and strong currents can overpower even experienced individuals. The increased risk of drowning is linked to the difficulty of escaping powerful rip currents and the danger of being struck by large breaking waves.
It is important to maintain a significant distance from the water’s edge and any structures exposed to the open ocean. People should avoid walking on jetties, rocky outcrops, and piers during these times, as these locations are frequently subjected to sudden, destructive wave wash.
Spectators should never turn their back to the ocean. The unpredictable nature of sneaker waves means a calm moment can be instantly followed by a dangerous, large surge. Keeping children and pets secured and away from the shoreline ensures they are not inadvertently swept away by unexpected wave run-up.