Storm Surge Risk

Posted on: August 10, 2011 by Larry Neilson

Vulnerability to Florida Coastal Cities High

Although Tropical Storm Emily did not make it’s way to south Florida, other hurricanes and storms will come our way, and it is important to understand the risks associated with storm surge.

Storm surge from a hurricane is often the greatest threat to life and property.  The rise of the ocean associated with many major hurricanes that made landfall has resulted in large death tolls.

Storm Surge vs. Storm Tide

Storm surge should not be confused with storm tide.  Storm surge is an abnormal rise of water generated by the high winds created by a storm.  Storm tide is the rise in water level due to the combination of storm surge and the astronomical tide.

Factors- The factors that determine the heights of a surge include the speed, intensity, size of the radius of maximum winds, radius of the wind fields, angle of the track relative to the coastline, the physical characteristics of the coastline, and the bathymetry of the water offshore.  The SLOSH (Sea, Lake, and Overland Surges from Hurricanes) model is used to simulate surge from tropical cyclones.

Records- The highest storm tide in historical accounts was produced by the 1899 Cyclone Mahina, estimated at 43 ft in Australia.  In the United States, one of the greatest recorded storm surges was by Hurricane Katrina in 2005, which produced a surge of more than 25 ft.

Six years after Hurricane Katrina devastated New Orleans; it may come as a surprise that the metropolitan area with the most to lose from storm surges is the South Florida complex of Miami-Dade, Broward and Palm Beach counties.

The Great Miami Hurricane of 1926, which hit downtown Miami and Miami Beach as a Category 4 storm, still ranks first in terms of damage, at $157 billion, when costs are adjusted for 2005 dollars according to a study by University of Colorado and National Hurricane Center.

One study by First American Corp., a company that provides risk information to insurance companies, shows the potential effects of hurricanes on homes in 13 Atlantic and Gulf coast communities. The study found that the storm surge associated with a Category 5 hurricane could damage more than 250,000 homes in southeast Florida at a cost of $53.6 billion, compared to $33 billion for Tampa, Florida.

South Florida has three of the most risky residential ZIP codes in the United States for surge effects from a Category 5 hurricane:

Rank      Zip Code               City

6th         33480                    Palm Beach

9th         33156                    Miami

10th       33157                   Miami

 

Posted in: Florida Businesses Florida Hurricane Season

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