Hurricanes

Hurricanes are the most powerful weather phenomena on earth. The energy packed into an average hurricane is enough to provide electricity to Great Britain for a year. Some storms can create "sea surges" up to 25 feet above normal, completely flooding the shoreline,wiping out settlements along the coast and tossing boats around like playthings. In some cases, 90 percent of the fatalities caused by a hurricane are drowning deaths. And usually it is the water, not the wind, that does the most property damage.

Just off the coast of West Africa, small storms that first develop over the continent drift slowly westwards, carried on the otherwise romantic and helpful trade winds. As the storms move inexorably towards the New World, they often begin to pick up speed, fueled by the warm Atlantic equatorial and tropical waters.

As a storm gathers steam, it becomes what meteorologists call a tropical depression, a system of cyclonic counter-clockwise-rotating clouds and moisture whose centre is an eye of abnormally low atmospheric pressure. Already it will be producing rain and squalls, but its winds will not exceed 38 miles per hour (33 knots).

Its next stage is a tropical storm, where winds can reach 60 or 70 miles per hour.As the storm grows, impelled by its own whirling and the rapidly evaporating sea water beneath, it evolves into a hurricane - whenever maximum sustained winds exceed 74 mph (64 knots).

Then it gets a name. Every year the Hurricane Center in Miami names 21 hurricanes in advance - and in alphabetical order. The names are selected for their ease of pronunciation in all Roman-letter based languages, with names customarily drawn from English, French and German.

When weather forecasters are satisfied that a hurricane exists and poses even the remotest threat to populated areas, they issue a hurricane watch. These watches go into effect long before the storm is near land, normally providing plenty of time for people to prepare. When forecasters get a bead on the storm, they plot its likely track - a track that is always subject to change - and issue a hurricane warning to those areas at risk. This warning is no drill. It's time to get ready.

Forces that are themselves often unpredictable determine the paths of hurricanes. In the Caribbean, weather frontal systems that typically migrate in an easterly direction from the continental US can push a storm abruptly northwards, sending it harmlessly into the North Atlantic, where the colder water will usually dissipate its force. But if these systems are weak or non-existent, the hurricane will usually barrel right across the Caribbean Sea and into the Gulf of Mexico, sometimes even gaining intensity on the way.

Remember that hurricanes are fickle, and can change direction and intensity surprisingly quickly, catching even the experts off guard.

Assume nothing.
Expect the worst.

Meteorologists rank hurricanes into five categories 1 being the mildest and 5 being the strongest. When forecasters announce a hurricane warning, the category of the hurricane is always included in the information. Your preparations can be made easier by referring to the description of each category so you know what to expect.

CATEGORY 1
Maximum sustained winds of 74 to 95 mph. Barometric pressure in the eye no less than 28.94 inches of mercury. Minimum damage to shorelines. No buildings, but trees and shrubs could be uprooted or stripped of leaves. Some flooding likely. Storms surges (rise in sea level) of no more than five feet.

CATEGORY 2
Maximum sustained winds of 96 to 110 mph. Barometric pressure in the eye no less than 28.30 inches of mercury. Potential for serious damage to building and flora. Roofing and windows could be threatened. Storm surges to eight feet. Storm craft in jeopardy.

CATEGORY 3
Maximum sustained winds of 111 to 130 mph. Barometric pressure no less than 27.91 inches of mercury. Damage likely to buildings and service. Fallen trees and utility poles could block roads. Storm surges of up to 12 feet, with severe coastal flooding and erosion.

CATEGORY 4
Maximum sustained winds of 131 to 155 mph. Barometric pressure no less than 27.17 inches of mercury. Heavy damage to structures, agriculture, roads and bridges. Roof damage very likely. Major beach erosion, heavy flooding. Storm surges to 18 feet.

CATEGORY 5
Maximum sustained winds higher 155 mph with gusts of 200 mph and higher. Barometric pressure lower than 27.17 inches of mercury. Extreme destruction to structures and all lifeline service. Complete roof failures and heavy damage to smaller buildings. massive flooding, with storms surges up to 25 feet. Evacuation necessary from areas on ground below 25 feet above sea level.