Storm Surge and Coastal Flooding

Storm surge is the abnormal rise of ocean water generated by a storm, measured as the height of water above the level that the normal predicted astronomical tide alone would produce. The dominant physical mechanism is wind stress: sustained onshore winds physically push a mound of ocean water ahead of the storm and pile it against the coastline as the storm approaches landfall. A secondary contribution comes from the inverse barometer effect, in which the sharply lowered atmospheric pressure at a storm's center allows the sea surface beneath it to rise slightly, typically by about one centimeter for every one millibar drop in pressure, a contribution that is real but generally much smaller than the wind-driven component except in the most intense storms. Historically, storm surge and the flooding it produces have accounted for the majority of tropical cyclone fatalities worldwide, far outpacing deaths directly attributable to wind.