Hurricanes are intense tropical low-pressure systems. They develop over tropical oceans during the spring and summer, deriving their energy from the warm water. Typhoons of the Pacific, cyclones of the Indian Ocean, and willy-willies of Australia are different names for the same atmospheric phenomenon. They can develop sustained wind velocities of over 150 miles per hour. Wind speed is, to a great extent, dependent upon the pressureÊgradient between the outside and inside of the storm. They may be 400 miles in diameter, but normally are much smaller.
Between 1900 and 1989 Florida experienced fifty-six hurricanes. Most have been categorized on the Saffir/Simpson scale (see chart) as minimal or moderate. Hurricanes reach Florida with greater frequency in September than any other month. It is at that time that air and ocean conditions are best for their creation and development. Hurricanes evolve from weak low-pressure systems. Evolution usually begins in the Atlantic, but they sometimes are born in the Caribbean and even the Gulf. Water temperatures must be high, and no hurricane has reached Florida before June or after November. June and November storms have been notably weaker than those of September, when water temperature is highest. Few of these weak systems ever pass into the hurricane stage.
These tropical storms tend to drift westward. The path of a hurricane is governed by pressure systems that it encounters as it moves. Very often hurricanes meet high pressure systems over the United States. These deflect them. Their paths then often begin to turn northward. Although this path followed by hurricanes has been less frequent in recent decades than in the past, it is still sufficiently common that the coast between the Florida Keys and Cape Canaveral has become known as hurricane alley. Since 1970 the northwestern panhandle of the state has experienced an unusually high number of hurricanes.
Hurricanes have brought tragic loss of life and property to Florida. Early evidence of their ferocity can be found in the many sailing ships - some loaded with treasure - lost by the Spanish along the Atlantic coast. In this century hurricanes have claimed almost 3,000 lives and property loss (in 1989 dollars) has reached nearly 6 billion dollars.
Until the middle of this century the state did little to protect property or to prepare the population for hurricanes. Hurricanes in 1926 and 1928 killed hundreds of people when a levee that held back the waters of Lake Okeechobee broke. The strongest hurricane ever to hit Florida occurred on Labor Day 1935, drowning many on the Florida Keys. These early disasters motivated the state to prepare the population for hurricanes and to adopt stringent building codes. Since 1945 fatalities have been far fewer. Despite greater development regulation, hurricanes continue to damage property primarily from flooding. Most hurricanes are accompanied by huge amounts of rainfall and also, along the coast, by storm surge.
