Monday, May 26, 2014

Hurricane Preparedness Week: Storm Surge

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# 8666

 

This is day two of 2014’s National Hurricane Preparedness Week and the focus today is on Storm Surge, traditionally the biggest cause of death from these killer storms. Having spent a good portion of my life as a liveaboard boater on Florida’s West coast, I can assure you from personal experience that storm surge can be both dramatic, and dangerous.

 

First stop, a short video from the NHC (National Hurricane Center), and a NHC description of storm surge, after which I’ll return with a bit more:

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Storm Surge vs. Storm Tide
Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases.


Storm Surge vs. Storm Tide

 

Back in 2011,  in Getting SLOSHed For Hurricane Season I wrote about the Sea, Lake and Overland Surges from Hurricanes computer model that emergency planners use to plan for coastal evacuations. In order to know in advance how far inland a storm surge or tide will encroach, emergency planners run hundreds of SLOSH models for populated regions along the coast. 

 

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They vary the size, intensity, direction, and forward speed of hurricanes in the model in order to determine the worst case impact for each category of storm. Evacuation maps and routes are then generated using this information.

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This evacuation map of Pinellas County (St. Petersburg-Clearwater) Florida shows that a storm even as low as a CAT 3 could temporarily cut the southern half of the county off from the north.

 

Of course much depends upon the speed, direction, and point of landfall of the storm, and so not all CAT 3 storms impacting this area would produce this dramatic of an effect. But if you are asked to evacuate by your local authorities, don’t hesitate.  

 

Just do it.

 

Which is why, the smart money is on deciding where you will go long before hurricane season arrives.  Public shelters are likely to be uncomfortable and crowded, and should really be your option of last resort.   A better plan is to pre-arrange with family or friends for a place to stay. 


As we discussed yesterday, this year, the NHC will be issuing enhanced color-coded experimental Potential Storm Surge Flooding Maps showing the locations that could be affected by storm surge based on their (SLOSH) computer models.

 

If you haven’t already downloaded the updated Tropical Cyclone Preparedness Guide, now would be an excellent time to do so.

 

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