Hurricane Preparedness Week Article #2-Surge & Marine Safety

[JonathanBelles]

Hurricane Preparedness Week Article #2

Monday May 26th, 2008-Storm Surge and Marine Safety

Now that we have seen what history has brought, we shall now see the forces that a hurricane can bring. Today we will go over Storm Surge and Marine Safety.

Surge

A simple definition of storm surge is the water that is shoved up the coast by the strong winds associated with the hurricane on top of the average current tide. The tide and the surge together are called the Storm Tide. This surge of water, as Ill call it, can raise the water level up to 20+’, but is usually less than that. Most loss of life at the coast line, where most people live, is caused by this surge of water.
Surge is usually worse where the slope up to land is gradual, where it is happening in a bay, inlet, bayou, marina, or harbor, or when the hurricane is coming into the landmass at a 90 degree angle. Surge is worse where the continental slope is shallower and more gradual because the water does not have to push up over a shelf or a cliff. Also, more water can build up with out being left behind on a more gradual slope. Water being shoved into a bay or bayou acts as if it were going into a funnel. It gains force and height as it moves through the funnel and then barrels through the end of the funnel into a neighboring community. If a hurricane is moving at a 45 degree angle some of the wind that pushes the water is not accumulated and is not as direct to the shore, so surge is not as bad. If the hurricane comes in at a 90 degree angle to the shore, the water is coming in at a direct angle and piles up for longer with more force.
Surge is also worse with a larger or a stronger hurricane. The surge of water is worse with a larger hurricane because more water is being moved into a more widespread area. Surge is worse with a stronger hurricane because there is more wind to push the water further inland with greater strength.
Surge also has to leave an area, and often that can be worse than the inundation. Because most areas have an upslope of land, water with gravity must come back down. This can create a sucking of water that pulls debris, people, houses, and cars back to the ocean. Also on the left (and usually west side) water is pushed out of areas with the wind.
Storm surges cause the most structural damage. Storm surge can severely erode beaches, split islands in half, wash out islands completely, and inundate cities as seen in Katrina. Evacuation maps are built around how far inland surge can go, and because the surge is one of the greatest killers, those maps need to be adhered to.
When Surge enters an estuary, the salt water can overwhelm the freshwater, which can wipe out entire species from an area. Even if surge isn’t going into an estuary, it still can cause animals to evacuate an area, possibly forever.

Surge Safety!
If you know you’re in an evacuation zone and a hurricane is coming…evacuate.
You don’t have to go across the state to be safe.
Make sure you have enough gas and money before the storm comes
Pick up anything that can be carried away by water
If there is water on the road…don’t cross it and get stuck
Turn around, Don’t drown is a very good rule of thumb


Marine Safety

Obviously you wouldn’t want to be in a boat near a hurricane, no matter the size or shape of the craft. A boater should watch and track all tropical systems that are within a thousand miles of the boat. They should also know the conditions that are favorable and when they are available to the atmosphere for development of storms. Any boater should know that a thunderstorm can change weather conditions nearly instantaneously.
Know the basics of hurricanes. Hurricanes usually have a parabolic path, and they usually accelerate in the poleward half of the parabola. Know that with warmer water, there is a chance of intensification. Boaters should also know that hurricanes can change intensity and direction in a few hours.
The National Hurricane Center has a few products to help boaters negotiate the risk of boating. One is the 34KT rule, which basically says a boat should not go anywhere where the winds are at or above Tropical Storm strength. The second tool is called the 1-2-3 Rule. The 1-2-3 rule gives the distance at which you should stay away from an area at a certain time. The rule states that you should be 100 miles away from the area in 24 hours, 200 miles in 48 hours, and 300 miles away in 72 hours. These are just guidelines, and conditions can change and the 1-2-3 rule will likely change day to day.
If a hurricane, or a tropical storm, is or will be within a few hundred miles of port or within your path, don’t leave port. Take a ‘better safe than sorry’ attitude with you when you are boating.

How to keep your boat safe in port

Even if you decide to keep in port, your boat may still be at risk from wind and waves against the shore. If you can take your boat out of the water, that is the best option, and to move it to high ground. If you can’t take your boat out of the water, it will need to be secured in a marina. Make sure you put your boat into what is called the spider web hold. Basically what that is, is attaching strong ropes to the front, side, mid-side, and back of the boat and attaching those ropes to the poles on the dock. Be sure to take out any loose objects and all important papers and equipment from the vessel before you leave it. Also remember that drawbridges will be locked down ahead of a hurricane, so boat traffic to safer marinas will be limited.


Hopefully with this information you and your boat will be safe from the wrath of the sea.