When Hurricane Katrina roared ashore in Louisiana in 2005, it brought the unrelenting waters from the Gulf of Mexico. Entire neighborhoods and communities were swept away or buried beneath ocean waters. Over 1,500 people lost their lives, most falling victim to Katrina’s unforgiving storm surge.
According to the National Hurricane Center and Central Pacific Hurricane Center, “Along the coast, storm surge is often the greatest threat to life and property from a hurricane.” It is attributed to about half of all deaths from a direct impact.
With all there is to consider with hurricane preparation and shopping for hurricane COVID supplies, it is important to account for another oft-overlooked side effect of hurricanes: storm surge.
What Is a Storm Surge?
Hurricanes and tropical cyclones are types of storms that form over water, generating significant energy and stirring up wicked winds. This storm can displace water, propelling it forward toward land. This is known as storm surge.
The National Oceanic and Atmospheric Administration (NOAA) defines storm surge as excess water that results in an abnormal rise above normal astronomical tides. When a storm pushes too much water to land, it can overflow and come rushing onto shore, creating significant devastation. Storm surge results in storm tide, which is the rise in ocean level created by storm surge.
Dr. “Hurricane Hal” Needham, Ph.D., is the in-house storm surge expert for CNC Catastrophe & National Claims. He has over ten years of experience tracking hurricanes and spoke to us exclusively regarding hurricane storm surge.
“Storm surge threatens to inundate low-lying areas where strong onshore winds push saltwater on land,” he explains. “Storm surge moves inland like a raging river of water, causing high amounts of fatalities and property damages. In flat areas, like southwest Louisiana, storm surges can push inland for more than 20 miles.”
Storm surge is dependent on a unique culmination of several factors:
- Storm intensity
- Forward speed
- Central pressure
- Radius of maximum winds (RMW)
- Angle of approach
Where Storm Surges Commonly Occur
NOAA uses the Sea, Lake and Overland Surges from Hurricanes (SLOSH) model to assess an area’s risk of flooding and storm surge. It is used to measure the coastlines of both the U.S. Atlantic and the Gulf of Mexico, where hurricanes and storm surge are greater risks. Hawaii, Puerto Rico, the Virgin Islands and the Bahamas are also included for a total of 37 basins.
Some geographic locations may especially fall susceptible, including certain bays and estuaries that pose a favorable layout and conditions for flooding.
Hurricane Hal is also a lead author on a pivotal 2015 study that reviews storm surge across the world, and he cites this study when explaining the details of storm surge. “Impacts vary by location, dependent largely on the elevation of an area, as well as the coastal profile,” he explains. “Shallow offshore water enhances storm surge levels, and these levels can be increased additionally by the presence of bays, inlets and other concave-shaped water features.”
These are the top U.S. cities most susceptible to storm surge and the estimated loss for a storm surge event.
- Tampa Bay, Florida - $175 billion
Half the population lives in low elevation areas, and Tampa Bay has the potential to flood surrounding cities.
- New Orleans, Louisiana - $130 billion
Extra low elevations and marshlands create ideal conditions for inland flooding.
- New York City, New York - $100 billion
This entire low-lying area is at risk of storm surge, thanks to coastlines along all five boroughs.
- Miami, Florida - $80 billion
Although protected by a steep shelf, Miami is still a favorable location for a direct hit from a Category 5 hurricane, and the amount of residential property along the water will face significant risk.
- Fort Myers, Florida - $70 billion
With few natural barriers, the majority of Fort Myers is located below 10 feet in elevation.
- Galveston-Houston, Texas - $55 billion
This area is also prone to storm surge, given its low elevation and prime position along the Gulf.
- Sarasota, Florida - $50 billion
Like Fort Meyers, Sarasota is a coastal community with few natural barriers for protection.
- Charleston, South Carolina - $45 billion
In addition to its low-lying areas, Charleston is also situated between two rivers that pose significant potential for flood and storm surge.
These areas all have low elevation, but there’s also another important feature at play here: the continental shelf surrounding these cities.
When there is a more shallow slope along the coastline, it makes it easier for water to sweep up and over land more easily, quickly inundating local communities. The more concave the area, the more likely it will experience storm surge. That includes all sorts of geographic areas, like bays, rivers, islands and headlands.
The Dangers of a Hurricane Storm Surge
Water is not light. In fact, it weighs 1,700 pounds per cubic yard, and when propelled by cyclonical pressure, it can produce deadly storm surge with powerful waves that will batter entire communities.
Storm surges also produce vicious currents that can easily wipe out beaches, erode roadways and seriously compromise the structural integrity of surrounding properties and buildings.
Depending on where you live, you may face several dangers. For example, enclosed harbors and marinas are prone to waves and currents in addition to storm tides. Meanwhile, the threat to estuaries and bayous is entirely different because these areas are not equipped for the invasion of saltwater that a storm surge brings. This can displace animal life, kill vegetation and pose a significant human health risk.
Additionally, NOAA reports that more than half of U.S. economic productivity occurs within the country’s coastal zones, including 72% of the nation’s ports, 27% of major roadways and 9% of rail lines. These areas are all located within or below a four-foot elevation that makes them extremely susceptible.
Worse, a storm surge of 23 feet or more could have the capacity to wipe out much of the Gulf Coast, including 67% of its interstates, 57% of arterials and nearly half of U.S. rail miles. It would also affect almost 30 airports and “virtually all ports in the Gulf Coast area.”
And it’s happened before.
Examples of Past Storm Surge
While Hurricane Katrina remains both the costliest and deadliest example of storm surge, there are many hurricanes in recent history that have produced significant damage from storm surge.
|Year||Storm||Type of Hurricane||Storm Surge||Estimated Losses||Number of Deaths|
|2008||Hurricane Ike||Category 2||15-20 ft||$24.9 billion||103|
|2005||Hurricane Katrina||Category 5||25-28 ft||$75 billion||1,833|
|2005||Hurricane Dennis||Category 4||7-9 ft||$2.23 billion||76|
|2003||Hurricane Isabel||Category 2||8+ ft||$3 billion||17|
|1995||Hurricane Opal||Category 3||10-20 ft||$3 billion||59|
|1992||Hurricane Andrew||Category||17 ft||$26.5 billion||26|
|1989||Hurricane Hugo||Category 5||19.8 ft||$8 billion||50|
|1969||Hurricane Camille||Category 5||24 ft||$1.42 billion||256|
How to Protect Yourself from Storm Surge
Prepare Your Community
In Hurricane Hal’s experience, one of the first steps you should take to safeguard storm surge is to prepare your community.
“Both structural and non-structural solutions can mitigate the impacts of storm surges,” he says. “Communities can build levees, seawalls and other structures to protect themselves against rising seawater. Natural strategies include the development of sand dunes, wetlands and other features that will provide some resistance to fast-flowing seawater.”
For the average homeowner, he has another suggestion. “Elevating homes and businesses above flood waters is another successful long-term mitigation strategy.”
If you live along the water or own a boat, always practice marine safety.
A hurricane’s path and intensity can change at a moment’s notice, so it is crucial to remain plugged into what’s happening outdoors even while you are trapped inside.
These are some of the best resources to protect yourself against hurricanes and storm surge.
NOAA Hi-Def Radar is another option as one of the world’s most popular weather apps. Bill Hess, its co-creator, explains, “This app is very popular in states with volatile climates as it provides both real-time and future (next few hours) updates for precipitation, hurricane/tropical storm, flooding and coastal alerts. The app has a strong audience with homeowners and could be a great addition for a simple and accurate way to track weather from a smartphone.”
How to Prepare for Storm Surge
To find out how best to prepare for storm surge, we spoke with Diane Vukovic. She is the lead writer at Primal Survivor and the author of her own book, Disaster Preparedness for Women. She walks us through how to prepare for an impending hurricane and its potential storm surge.
Before the Storm
- Make an evacuation plan.
“The most important thing to do for hurricane preparedness is to make an evacuation plan,” Vukovic says. “Under what circumstances will you leave? How much will evacuation cost? Having a plan means you will be able to leave sooner and avoid issues like massive traffic jams, lines at gas stations, or overbooked flights.”
- Fill your car with gas.
“Long lines form at gas stations before hurricanes,” Vukovic warns. “You can lose hours of valuable evacuation time waiting in line. There have been cases where gas stations even ran out of gas, leaving people stranded.”
- Create a hurricane kit.
“Your hurricane kit should include basics like bottled water, non-perishable food, a first aid kit and personal medications.”
- Move to a higher floor.
It’s a simple solution Vukovic recommends first. “An easy thing you can do to save your belongings from hurricane flood damage is to move them to a higher floor. Put all electronics and valuables upstairs, preferably in an interior room without windows.”
- Prepare furniture.
“It's not very practical to move heavy furniture upstairs, or you simply might not have an upstairs,” says Vukovic thoughtfully. “In this case, make sure to have some blocks ready. Put these under the legs of your furniture and refrigerator so they are higher off the floor.”
Don’t forget about your rugs, either. She explains, “Rugs act like giant sponges when they get wet and usually have to be thrown away after exposure to floodwater. You can save them by rolling them up and putting them on top of other furniture.”
- Clean your gutters.
“Huge amounts of rain hit your roof during a hurricane. If the gutters are blocked, the rain won't be able to escape down the gutters and will instead spill over the side of your roof,” says Vukovic. “The waterfall of rain will damage your home's foundation and siding. Make sure gutters get cleaned before hurricane season begins as well as again after a large storm hits.”
During the Storm
- Exercise proper generator use.
“Most deaths after a hurricane don't actually occur because of the hurricane itself. Rather, they occur because of carbon monoxide poisoning from incorrectly-used generators,” she explains. “It is CRUCIAL that you read your generator's instruction manual and understand the safety protocols before turning it on.”
Be sure to use your carbon monoxide detector. “As an extra safety measure, you should get a battery-operated carbon monoxide detector in your home to ensure your family isn't quietly being poisoned.”
- Use your radio.
Sometimes, you cannot count on cell phone or internet service to give you the information you need because systems can get overloaded and shut down during emergencies.
“You’ll need an NOAA emergency radio so you can stay informed about the situation, such as when the storm has passed and it is safe to leave your home.”
- Keep the correct tools handy.
“Floodwaters rise quickly, sometimes trapping people in their homes,” she warns. “Consider keeping an ax and lifeboat on an upper floor so you can escape. Emergency items should be kept in your safe room, which ideally is an interior room without windows. You don’t want to have to leave the safe room during the middle of the storm because you need to get your insulin or grab the flashlights after the power goes out.”
After the Storm
When the storm is over, and the waters begin to recede, there may be major damage to contend with.
Vince Perri, CEO of Commercial Claims Advocate in Florida, is personally acquainted with hurricanes and storm surge. “Growing up in Florida, hurricane preparation is something I am all too accustomed to, but one should never underestimate the power of mother nature. Always be ready!"
His tips include:
- “Take a lot of photos: photos of the exterior and every side of the home, photos of your roof, photos of the interior and every bedroom in the house. You do not want the insurance company to come back and say the damage was already there.”
- “Have your policy ready. Review the policy to make sure you know and understand your coverages before the storm hits.”
- “If there have been any repairs made to your home, have them in a location you can access to show the insurance company if need be during the insurance claims process.”
The Bottom Line
Responsible for approximately half of all direct hurricane deaths, storm surge is the dangerous result of cyclone winds that can push massive amounts of water onto shore. Be sure to stay informed and always take the right precautions to protect yourself if a hurricane is headed your way.