Influences
The level of storm surge during a storm is influenced by:
- Size and extent of storm’s wind field ("radius of maximum winds")
- Strength of storm winds (see animation)
- Storm’s forward speed
- Storm track
- Storm’s central pressure (contribution of pressure to total storm surge is small compared to wind)
- Landfall location
- Coastal elevation (much of the densely populated Atlantic and Gulf coastlines are less than 10 feet [3 m] above mean sea level, making them especially vulnerable.)
- Shape and characteristics of the coast (bays, rivers, etc.)
In addition, surge inundation in an area is also affected by the underwater topography ("bathymetry") off the coast–in particular, the slope of the continental shelf. A shallow slope will potentially produce a greater storm surge than a steep shelf. For example, a Category 5 storm hitting the Georgia coastline, which has a very wide and shallow continental shelf, may produce a 20-foot storm surge, while the same hurricane in a place like West Palm Beach, Florida, where the continental shelf drops off very quickly, might see only an 8 or 9–foot surge.
Battering wind waves on top of the total storm tide may increase damage along the coast. Water weighs approximately 1,700 pounds per cubic yard (~1,000 kg/cubic meter); extended pounding by frequent waves can demolish any structure not specifically designed to withstand such forces.
Although elevated, this house in North Carolina could not withstand the 15 ft (4.5 m) of storm surge that came with Hurricane Floyd (1999)
Additionally, currents created by tides combine with the waves to severely erode beaches and coastal highways. Buildings that survive hurricane winds can be damaged if their foundations are undermined and weakened by erosion.
Beachfront road and boardwalk damaged by Hurricane Jeanne
In confined harbors, the combination of storm tides, waves, and currents can also severely damage marinas and boats. And in estuaries and bayous, salt water intrusion endangers public health and can send animals, such as snakes and alligators, fleeing from flooded areas.
Damaged boats in a marina