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Hurricane Day 2 Storm Surge

Published by Annmarie Mudge Buckley in Weather Emergencies · 17/8/2015 14:47:00
Tags: hurricanestormsurge
Often the most damage and death caused by a hurricane is the flooding from storm surge. A major hurricane has the potential to push water more than 30 miles inland. Some areas that are not ravaged by flood waters (High Ground) end up cut off from aid and exit by flooding in the lower lying areas. As is the nature of animals, they move to higher ground when a storm is coming so high ground may be inundated with wildlife, insects and reptiles seeking safety.

Storm surge is the abnormal rise in water generated by a storm above the normal tidal height. The height of storm surge depends on several factors, the strength of the hurricane, the height of tide and the angle at which the storm comes ashore. The higher the tide as the storm comes ashore changes the height of the storm tide and thus the storm damage. For instance, if the astronomical tide is 2 feet above norm and the storm surge is 15 feet then the storm tide is 17 feet. Stronger storms have faster winds, wind causes about 85% of storm surge, the wind pushes the water into waves and creates larger more powerful waves that then push the water in front of it and so on and so on. The faster the winds, the faster the waves and the more water that gets caught up in the mix. As anyone who has walked outside in the wind knows, straight on in the wind has more force than if the wind is passing you at an angle. The same applies to where and how the storm surge will approach shore. If it is heading to shore straight on it is more powerful than if it is moving along at an angle or to the side. For a good example of it watch the wake of a moving boat and where the wake makes its way to shore, the splash is louder where the wave hits dead on and softer almost a ripple where it moves to the side.

Why are storm surges so deadly:

If you have ever waded in the ocean, six inches of moving seawater is difficult to stand in. A foot of moving seawater can lift a car and move it. Add to the force of the flowing seawater the fact that it is carrying debris and now there is a moving force with shrapnel to help with the damage. As the water flows, it soaks everything in its path and fills all the space available. If water flows into a home, it will build up on the walls until it finds a release.

In most circumstances, being low to the ground protects from wind damage and safety in solid foundations and inside buildings can help improve the chances of surviving a wind event, water on the other hand does not allow for it. Water fills up the lower spaces, pushes everything in its path and moving to higher levels is helpful to keep from being pushed under but water attacks the area below you and could take out the supports causing you to float away as a piece of debris. Storm surge also causes more problems in that the situation doesn't end when the water recedes, then it leaves behind mold, bacteria and dirt causing illness and more damage.

The National Oceanographic and Atmospheric Administration (NOAA) has a good interactive map where you are able to see the predicted flooding of an area for different category storms. These are worse case scenarios and predict a storm surge at high astronomical tide and a head on angle. Knowing where you are at worse case is important as storms change angle, speed and time to landfall and waiting to see may find you trapped on the roof of you house in pounding rain and wind praying for a rescue that isnt going to come for days.

Now when you use the link below, I'd like you to click on the "Category 3" tab. This is likely the worst case scenario for Charleston SC to Jacksonville Florida. Category 4-5 storms typically don't acquire the energy needed in the time it takes to get from the Caribbean to our area ( Thank God). Now, zoom into the Charleston-Savannah area. See all of those red dots? Thats NINE FEET of water. Even in a Category 1 storm, the areas from Tybee to Thunderbolt will likely see a minimum of 3-4' (thats FEET folks...FEET) of water inundation. Thats not even the scary part. On Tybee, you will be able to see the water getting higher as it violently crashes onto and into the dunes, seawalls, houses, and surf breaks. Not so as the water progresses inland. As anyone on Wilmington Island will attest to, it is a long way from the seawall on Waltour Rd.(the side of the Island that faces Tybee) at any particular tide, to the water. When storm surge is done with Tybee, it will be on its way here to Wilmington. It will not be as bold or scary. Almost magically it creeps up through the marsh with little to no fan fare. THIS is what kills. Water will 'appear from nowhere'. You will be standing with dry feet in Wilmington Park and three minutes later it will be up past your knees. At ten minutes, it will be above your waist. No waves, no sound, the water will simply rise. At thirty minutes into the storm, getting off of Wilmington even aboard a vessel, will be challenging. You will not get off the Island in a vehicle. Keep in mind also, these waters will be full of sewage, ants, snakes, well you get the picture. Take a few minutes to play with the link below, when you are done, come back and we'll talk more about how NOT to be there in the first place.

Evacuation is the only way to guarantee safety.

Have an evacuation plan, if you live in a coastal region, even if you are on high ground for that region, have a way out when the storm in 72 hours away. Please do not wait until you are forced to leave or worse, a Police Officer comes to your door with a Sharpie. Thats right, he's going to have you write your name, DOB, and SSN on your arm. Thats so your body can be identified after the storm. Facts are facts, you guys. I personally have worked the aftermath of major storms. I have had to tell families that all we ever found of their loved one is whats in the 1 gallon zip lock bag, and were not even sure its them, but his/her wedding ring had initials in it that matched a missing member of this community. Its one of the hardest things I've ever had to do. Please evacuate at the first sign that the storm in coming. Thats usually at the 72 hour mark. Thats a decent, safe, and productive time to put your Action Plan into effect. Evacuation routes for Chatham County are typically US-80, I-16, I-95, GA-280, and others clearly marked with the blue and white STORM ROUTE signs.  

If you can evacuate at the 72 hour mark, its likely you will not incur much traffic and/or congestion. Things have changed a lot in just the past 4-5 years. Attitudes toward the old 'you need to stay here and work until they tell us to leave...' simply aren't the norm any longer. Any employer who tries things like that can be referred to the 'Willful Disregard' and 'Wreckless Endangerment' Statutes that are now in force under Federal Law. After Hurricane Katrina, these laws and protections became common sense, so if you need to take the time to get your family together to evacuate SAFELY, you can and should. As discussed earlier, even if you don't flood, if the area surrounding you is flooded you will not be able to get to safety and the local wildlife will be using your backyard for refuge. Click here to find the evacuation routes by State and follow those links to your location.

A good evacuation plan accounts for where, when, how and who. Most importantly, designate a meeting location if you are separated and an outside contact for messages. For instance, a family member who lives in the Midwest outside the storm zone would be a good contact person, everyone contacts them and they relay messages when communication is limited.

Start your own evacuation plan.

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