Storm Surge

ocean · weather · disaster

Water gets shoved ashore. When a tropical cyclone or hurricane moves over the ocean, its low pressure and powerful winds push enormous amounts of water toward the coast. This water rises well above the normal tide level, sometimes 20 feet or higher, flooding cities and towns near the shore.

It's part of the storm. Storm surge is different from regular waves because it's one massive, continuous rise in water level caused by the storm itself. It doesn't include the individual waves you see crashing on the beach.

Measured above normal tide. Scientists measure storm surge by comparing the water level during the storm to what the water level normally is at that same location and time. The difference tells them how much the storm pushed the water up.

Two forces at work. The water rises because of two things: the super low air pressure above the storm (which lets water bulge upward) and the storm's fierce winds that literally push water toward land like a giant shovel.

Dangerous to coastal areas. Storm surge is one of the most destructive parts of hurricanes and tropical cyclones because it floods neighborhoods, damages buildings, and can trap people who don't evacuate in time.