As hurricanes come ashore, they cause destruction via heavy rain, high winds and storm surge; the latter is often least appreciated by coastal residents and visitors. The amount of rainfall is most closely related to the forward speed of the hurricane; the slower it moves, the more rain it drops on any given area. The wind damage correlates with the strength of the hurricane; the lower the central pressure, the higher the sustained wind speed and, thus, the greater the impact on structures.
The storm surge refers to the buildup of ocean water ahead of the storm. As the hurricane comes ashore, it acts like a giant plow, forcing a broad river of water toward the coast; this phenomenon is greatest to the right of the storm's center, reflecting the counter-clockwise motion of the surface winds. The threat from storm surge is related to the size of the hurricane and to the region's topography; flat coastal plains that lie along shallow bays are especially vulnerable.
If the coastal water is deep and the impact area broad, the plowed water can displace downward and outward, minimizing the surge; however, if the sea is shallow and the topography funnels the flow into a bay or river valley, the building surge has no escape and a devastating flood develops.
Hurricane Ike, currently a category 2 storm, is forecast to strike the northern coast of Texas tonight. Gulf waters are relatively shallow in that area and coastal bays to the right (north) of the landfall will experience the greatest inflow of water. A storm surge of 20 feet is expected; any land (and structures) below that elevation will be underwater.
