The high winds associated with tropical and extratropical storms can cause extreme waves and storm surges. Storm surges, caused by a combination of low barometric pressure and high onshore winds, can raise sea level by several meters. Waves and storm surges are responsible for severe flooding and property damage.
Extreme waves along the Atlantic coast are often produced by both intense extratropical storms and tropical storms. Extratropical storms range from "bombs" (small, intense, rapidly developing storms) to large, almost-stationary storms. Tropical storms, including hurricanes, can also produce extreme wave conditions along the coast. Particularly at the coast itself where storm surges of 10 ft or more can accompany waves, hurricane waves represent an extreme threat to both life and property.
The primary source of extreme waves in the Gulf of Mexico is hurricanes. Hurricanes Betsy (1965), Camille (1969), Carmen (1975), Frederick (1979), Alicia (1985), and Andrew (1992) have clearly shown the devastating potential of these storms in the Gulf of Mexico.
Tropical storms are not very common along the Pacific coast of the United States. However, swell from tropical storms spawned off the west coast of Mexico and from large winter storms in the Southern Hemisphere can become important elements in the summer wave climate. Winter storms in the North Pacific also cause extremely energetic wave climates that can damage shoreline structures and severely erode coastal areas. Extreme waves measuring nearly 40 ft have been recorded off the coast of Oregon during the winter months.