Storm Surge

A Storm surge is an abnormal rise in water level, over and above the regular astronomical tide, caused by forces generated from a severe storm’s wind, waves, and low atmospheric pressure. Storm surges are extremely dangerous, because they are capable of flooding large coastal areas.

Storm Surge is the Leading Cause of Coastal Floods

Very intense storms – like hurricanes – can generate large and devastating surge. Storm surge occurs when the winds push water toward the shore. The low pressure associated with intense storms has a small effect on surge as well. The size of a storm surge for a particular location depends on a number of factors. Storm surge is very sensitive to the shape of the coast, and to changes in storm track, intensity, forward speed, and size. Tidal height at the time of maximum storm surge is an important factor, too. (The combined effect of the storm surge and the astronomical tide is called the storm tide.) The slope of the sea floor also influences the level of surge in a particular area. Areas with a shallow slope of the sea floor off the coast will allow a greater surge. Areas with a steeper slope will not see as much surge, but will generally have large breaking waves that can destroy lower elevation buildings near the coast and open bays.

Areas Most at Risk

Coastal areas and barrier islands: Because they have few evacuation routes, barrier islands are especially vulnerable to hurricanes and flooding. Local officials will usually ask people on barrier islands and in vulnerable coastal areas to evacuate well in advance of a storm’s landfall. If they ask you to evacuate, do so IMMEDIATELY!

Low-lying inland areas: It is not often clear which parts of a community are most vulnerable to floods, since they may not be closest to the coast; however, if they are low-lying or near a waterway, they may be at a higher risk than assumed. Listen carefully to local authorities to determine what threats you can expect and take the necessary precautions to protect yourself, your family, and your property.

What Can You Do to Prepare?

  • Know the types of hazards that could affect your family, and know your home’s vulnerability to storm surge, floods, and wind. Find out if you live in an evacuation zone or storm surge planning zone and keep track of which zone it is. If you live close to the floodplain, consider flood insurance.
  • Make plans for where you’ll go, preferably outside the vulnerable area, or consider the closest possible public shelter. Have a single point of contact for your family members to keep in touch. Make a plan now for what to do with your pets if you need to evacuate.
  • Stock non-perishable emergency supplies and keep a disaster supply kit within reach.
  • Prepare your home prior to leaving: board up doors and windows, secure or move all yard objects indoors, and turn off all utilities. Fill your car with gas, withdraw extra money from the ATM, and be sure to take all prescription medicines and special medical items, such as glasses and diapers.
  • If you live in an evacuation zone and are ordered to evacuate by state or local officials, do so as quickly as possible. Do not attempt to cross flowing water. As little as six inches of water may cause you to lose control of your vehicle.
  • Stay tuned to a local radio or television station and listen carefully for any advisories or specific instructions from local officials. Monitor your NOAA weather radio. Remember to replace its battery every six months, as you do with your smoke detectors.
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