Why are evacuations ordered during hurricanes?
One of the biggest decisions for local officials during a hurricane threat is whether or not to call for evacuations. A recent survey indicates that most people think they are told to evacuate because of the wind in a hurricane. This is incorrect. The main reason evacuations are ordered is because of the storm surge.
A scientific paper published in the Bulletin of the American Meteorological Society by National Hurricane Center Deputy Director Dr. Ed Rappaport, on "Fatalities in the United States from Atlantic Tropical Cyclones," clearly shows the cause of deaths by various hazards over a 50-year period.
88 percent of storm related fatalities occurred in water-related incidents. Storm surge was responsible for about half of the fatalities (49 percent). Another 27 percent resulted from rainfall-induced freshwater floods, 6 percent from rip currents and large waves, and 6 percent from marine accidents within 50 miles of the coast.
Three percent of the fatalities resulted from tornadoes and another 8 percent from (non-tornadic) wind.
South Florida remembers Hurricane Andrew primarily as a wind event. But we need to understand that Andrew was an exceptionally small Category 5 hurricane and its storm surge was limited to a small area. The Great Miami Hurricane of 1926 was a much larger Category 4 hurricane that had a tremendous storm surge. 372 direct deaths are attributed to that hurricane and many of them were from storm surge.
If you live in South Florida, it is absolutely essential that you know what storm surge planning zone you live in. Large loss of life from storm surge in Hurricane Katrina and Superstorm Sandy are recent reminders of the power and danger of storm surge.