Hurricane Hazards

Storm surge, floods and winds

Storm surge is a great dome of water often 50 miles wide, that comes sweeping across the coastline near the area where the eye of the hurricane makes landfall. The surge, aided by the hammering effect of breaking waves, acts like a giant bulldozer sweeping everything in its path. The stronger the hurricane, the higher the storm surge will be. This is unquestionably the most dangerous part of a hurricane. Nine out of ten hurricane fatalities are caused by the storm surge. During the infamous Hurricane Camille in 1969, a 25-foot storm surge inundated Pass Christian in Mississippi. Lesser height are more usual but still extremely dangerous.

Many factors are involved in the formation and propagation of a storm surge such as the strength of the storm, bottom conditions where the surge comes ashore, and the point in the storm center in relation to the shore.

Floods and flash floods brought by the torrential rains of a hurricane are dangerous killers. Even though hurricanes weaken rapidly as they move inland, the remnants of the storm can bring 6 to 12 inches of rain or more to the area it crosses. The resulting floods have caused great damage and loss of life. Hurricane Diane of 1955 caused little damage as it moved into the continent; but long after its winds subsided it brought floods to Pennsylvania, New York, and New England that killed 200 persons and cost an estimated $700 million in damage. In 1972, Agnes fused with another storm system, flooding creek and river basins in the Northeast with more than a foot of rain in less than 12 hours, killing 117 people and causing almost $3 billion damage. Hurricane Beulah of 1967 brought major floods to southern Texas killing 10 persons and causing millions of dollars damage.

Winds. The winds of a hurricane by definition 74 miles an hour or more can be very dangerous. For some structures, wind force is sufficient to cause destruction. Mobile homes are particularly vulnerable to hurricane winds. Some hurricanes spawn tornadoes which contribute to incredible destruction. The greatest threat from a hurricane's winds is their cargo of debris, a deadly barrage of flying missiles such as lawn furniture, signs, roofing, and metal siding.