CDM - Hurricanes & Tropical Storms
Hurricanes & Tropical Storms


A hurricane is a tropical cyclone where the maximum average wind speed near its centre (eye) is more than 74 mph or 119 Km/h. The winds rotate in a counter-clockwise spiral motion around a region of low pressure.

The hurricane is one of the most damaging and potentially deadly disasters which can affect the Caribbean.

How are they made?

A hurricane must be over water to form. They are created over warm, tropically heated water, usually near the equator. This usually happens during the hurricane season, which lasts from June to November each year.

To understand what it takes to make a hurricane, we must first understand how the earth’s atmosphere works. As air gets closer to the ground it gets warmer. Over oceans, this warm, moist, low pressure air will rise and condensate, to form clouds and rain. Condensation releases heat, which warms the cool air at the top and causes that to rise as well. When this cool air rises, it is replaced by the warm air that came from below. This transfer of heat causes circling winds to rotate about a centre – like water going down a drain. The heat is the fuel for a hurricane.

There are four phases in a hurricane’s development. Hurricanes usually start off as tropical disturbances and then as the intensity of the winds increases, they’re upgraded – so to speak – to tropical depressions (winds less than 38 mph), tropical storms (winds between 38 mph & 74 mph) and finally hurricanes (winds more than 74 mph).

After the disturbance becomes a hurricane, it can be upgraded even further. There are different categories of hurricanes (1 through 5) which are changed as the winds grow stronger. This scale is called the Saffir Simpson Scale and can be seen below:


Central Pressure
Mean (millibars)

Wind Intensity


Storm Surge(ft)

Extent of Damage

Example of a Storm


980  or more

74 - 95mph (119 - 151km/h)



Anges 1972


965 - 979

96 - 110mph (152 - 176km/h)



Kate 1965


945 - 964

111-130mph (177 - 209km/h)



Elena 1985


920 - 944

131 - 155mph (210 - 248km/h)



Hugo 1989


less than 920

more than 155mph (248km/h)

more than 18


Gilbert 1988


As they move ashore, hurricanes and tropical storms bring with them a storm surge of ocean water along the coastline as well as high winds, torrential rains, and flooding.

High winds and heavy rains are probably the most deadly characteristics of the storm. Heavy rains can cause floods, landslides and mudslides, while strong winds can destroy crops and homes. Like any disaster, the worst thing about a hurricane is the damage it leaves behind.

Physical Damage
Structures will be damaged or destroyed by wind force, storm surges, landslides and flooding.  Public utilities such as overhead power lines, water and gas distribution lines, bridges, culverts and drainage systems can also be severely damaged.  Fallen trees, wind driven rain and flying debris can also cause considerable damage. 

Crops and Food Supplies
The combination of high winds and heavy rains and floods can ruin crops and trees. Food stocks may be lost or contaminated and it is very possible that food 
shortages will occur. After the storm has passed, the destruction of crops can impact the agriculture industry this is especially true for countries that depend on food exports to drive their economies.

Casualties and Public Health
Relatively few deaths are associated with the impact of high winds. However, storm surges may cause many deaths but usually few injuries among survivors. The threat to public health emerges in the after the hurricane had passed when conditions such as water contamination or water shortages, flooding and damage to sanitation facilities may favour the spread of diseases. 

Lack of Communication
Communication may be severely disrupted as telephone lines, radio and television antennas and satellite disks are blown down. Roads and railway lines may be blocked by fallen trees or debris and aircraft movements are curtailed for hours after a storm or hurricane.


Hurricane Janet
1. When?

              September 1955


              After it formed to the east of the Lesser Antilles, it quickly became a small hurricane and hit
              Barbados as a Category 3 hurricane. It continued through the islands, causing heavy
              damage in Grenada and the Grenadines. Janet became a category 5 hurricane before
              hitting Mexico and causing damage to Belize. Janet reached a peak of 175 mph winds in the
              western Caribbean Sea, making it one of the most intense Atlantic hurricanes on record.


              Janet reduced many cities to rubble. It claimed 32 lives in Barbados, damaged 8,100 homes
              and left 20,000 people homeless. In Grenada and the Grenadines, 122 were killed – the
              storm cost them US$2.8 million in damage. Janet killed 16 in Belize but the worst was
              Mexico, which was left with an estimated death toll of 500.

Hurricane Gilbert
2. When?

              September 1988


              Gilbert passed directly over Jamaica – it was the first hurricane to do so since 1951. After
              strengthening to a category 4 hurricane, it pounded Grand Cayman before crossing the
              Yucatan peninsula and devastating Mexico. Gilbert intensified until it reached peak winds
              of 295 km/h. This ranked it as having the third highest winds in a hurricane on record;
              only Camille and Allen had higher winds.


              Gilbert claimed 318 lives: 202 in Mexico, 45 in Jamaica, 30 in Haiti, 12 in Guatemala, 5 in
              Venezuela and the Dominican Republic, 3 in the United States, and 2 in Costa Rica and
              Nicaragua. The total for all areas affected by Gilbert was estimated to be near 5 billion
              USD in 1988.

Hurricane Ivan
3. When?

              September 2004


              It moved through the extreme Southern Windward Islands of Barbados and Grenada as a

              category 4 hurricane. It destroyed 75 to 90 percent of all buildings on the island of Grenada.
              It also affected Jamaica, Grand Cayman and Cuba.

              As it moved into the ocean, it strengthened to category 5 status before making landfall near
              Alabama, when it weakened to a category 3 hurricane.


              Ivan was responsible for an estimated 110 deaths throughout the Caribbean and the
              Eastern United States. It also damaged oil and gas facilities near Mexico. Initial damage
              estimates range from $4 to $10 billion dollars.

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