A storm surge is the part of the hurricane or cyclone that has brought most of the death and destruction. Once a hurricane or cyclone is predicted for an area, the storm surge is the main reason why coastal areas are evacuated as storms approach.
In a storm surge, the hurricane and tropical storm winds push a dome of water toward shores. These storm surges can be as large as 25 feet high and be 5001000 miles wide. The whirling winds around the hurricane's eye build the dome of water higher and higher.
The real fear and danger is in coastal areas where this building dome of water cannot be seen right away. It is as though the dome sinks and flows away, only to reappear as the storm nears land. Traveling closer and closer to shore, the contours and height of the the sea floor then influence and may even block the direction of the surge. With nowhere to go, the dome of water grows and grows, and needing another route, the storm's power comes ashore as this deadly wall of water.
The high death rate in a storm surge is due to drowning. It is nearly impossible to even imagine the force of storm surges that have ravaged the continents. Bangladesh, in 1970, over 300,000 people drowned in such a storm surge.
The worst impact is when the storm surge arrives with a high tide. This combination has such force that the storm surge can travel to areas resident think would have been safe. This situation is compounded by pounding waves resulting from such incredibly strong winds, especially in low lying areas.
Experts can forecast the direction of the storm surge. Scientists and meteorologists know that in the Northern Hemisphere, as you face the shoreline, he greatest storm-surge damage is to the right of a hurricane's eye. The storm surge builds to the right of the eye because winds, the rise in sea level, and ocean waves move in an onshore direction. Winds to the left side of the eye of the storm can reduce the power of a storm surge as these winds and waves are blowing away from the shore contrast, to the left of the eye, ocean waves and sea-level rise are moving in an onshore direction.
The physical geography of each coastline is a major factor in determining storm surge damage. This physical geography, along with the wind, waves, and sea-level, all contribute to the full force of the storm-surge damage. It is the storm surge at the start of a powerful storm itself that makes the storm surge the most feared and devastating aspect of a hurricane or cyclone.