How Do Storm Surges Form?

A storm surge is a rise in sea level associated with a tropical or extratropical weather system. The storm surge is often the most deadly phenomena associated with tropical storms and cyclones.

Storm surges are formed as a hurricane or tropical storm moves across a large body of open water. Tropical weather systems have winds that are strong enough to produce a rise in sea level beneath the storm. The storm surge of a tropical weather system can cause intense flooding and even total inundation when the storm makes landfall in a coastal area.

There are many factors that determine the maximum potential storm surge that a weather system is able to produce including the size and intensity of the storm, its angle of approach to the coast and the slope of the continental shelf. The bulk of the surge occurs as the force of the wind pushes water toward the shore when a storm is making landfall. For storms in the Northern Hemisphere with a counter-clockwise rotation, the largest storm surge can be expected in the right-forward quadrant of the storm. Systems in the Southern Hemisphere rotate in a clockwise direction and have a larger surge in their left-forward quadrant.