A storm surge may occur during large coastal storms. Storm surge is the water that advances toward the shore by the force of storm generated winds. Most (>85%) of the storm surge is caused by winds pushing the ocean surface ahead of the storm. The sudden rise in water level can cause severe flooding in coastal areas, particularly when the storm surge coincides with periods of high tides. In areas where there is a significant difference between low tide and high tide, storm surges can be particularly damaging when they occur at the time of a high tide (National Hurricane Center 2009).