What is storm surge and coastal inundation?
Storm surge is one of the main causes of coastal inundation. Storm surge is the abnormal rise in water level, over and above the regular astronomical tide, caused by a severe storm such as a tropical cyclone or nor'easter. Large waves also raise coastal water levels and ride on top of the storm surge to cause extreme damage.
Coastal inundation is the flooding of normally dry, low-lying coastal land, primarily caused by severe weather events along the coasts, estuaries, and adjoining rivers. These storms, which include hurricanes and nor’easters, bring strong winds and heavy rains. The winds drive large waves and storm surge on shore, and heavy rains raise rivers. (A tsunami – a giant wave caused by earthquakes or volcanic eruptions under the sea or landslides into the sea – is another kind of coastal inundation, but should not be confused with storm surge.)
Storm surges are extremely dangerous because they are capable of flooding large coastal areas, causing severe devastation.
To prevent disaster, avoid the water and waves, and when local authorities instruct you to evacuate, do so quickly!
If you are currently experiencing a storm surge event, visit your local National Weather Service weather forecast office website for information about local surge impacts under coastal flood watches or warnings and hurricane local statements:
“What areas are vulnerable to coastal inundation?”
All low-lying coastal regions, which can cover tens of miles inland, are vulnerable to flooding from storms, and the impact can be substantial.
- Much of the densely populated Atlantic and Gulf Coast coastlines lie less than 10 feet above mean sea level, within the reach of strong storm surge events.
- Over half of the Nation's economic productivity is located within coastal zones.
Bill Read, Former Director
“What kind of damage does storm surge do?”
Storm surge, associated with many major hurricanes and extratropical storms, can cause many deaths and devastating property loss. Storm surges have damaged roads and bridges, destroyed homes and businesses, and wiped out entire coastal communities. Hurricane Katrina (2005) is a prime example of the damage and devastation that is possible. At least 1500 people lost their lives during Katrina, and many of those deaths occurred because of storm surge, either directly or indirectly. Katrina also caused well over $100 billion in damage from its surge and winds.
“Can storm surge be predicted?”
Yes, advanced computer models are used to simulate the weather conditions in a severe storm to learn how it can cause coastal inundation conditions. The SLOSH (Sea, Lake, and Overland Surges from Hurricanes) model simulates surge from tropical storms to predict potential storm surge impact. NOAA has several models, such as an extratropical storm surge model, that predicts surge and its impact from extratropical storms.
“How do I know if coastal inundation from a storm will affect me?”
NOAA's National Weather Service monitors coastal inundation conditions 24 hours a day, 7 days a week. The Weather Service issues forecasts, watches, and warnings, with details on a storm's impact. Local emergency management officials use this information to decide when evacuations are necessary, and if they are, report them to media outlets. Keep track of the information provided by your local weather forecast office and listen to local media reports.
“What can I do to protect my family and property from potential storm surge?”
Be prepared. Know the hazards that may affect you, your family, and your home. Make plans for where you’ll go if told to evacuate. Have a disaster supply kit within reach. Stay tuned to local radio and television stations, and listen for advisories or specific instructions from your local officials. Monitor your NOAA weather radio.