June too soon! Tracking Caribbean hurricanes

Between June and November, storms and hurricanes are possible, Fortunately, weather disturbances are tracked from the moment they are born these days, giving everyone not only ample time to prepare, but also providing a wonderful opportunity to observe one of Nature's forces unleashed

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With its blue skies, idyllic beaches, calm turquoise seas and verdant vegetation, you wouldn’t think the Caribbean could be anything but benign. But, as luck would have it, the islands lie in the path of some of the most ferocious of tropical storms — the hurricanes which churn their way westwards across the Atlantic in late summer and early fall.

There was a time when the Caribbean islands would have little or no warning of the approach of one of these monsters. These days, of course, weather disturbances are tracked from the moment they are born, and every movement along their course is public knowledge. Forecasters can predict, days in advance, where a storm is likely to go; anyone with Internet access can watch a storm’s progress online. Airlines amend their flight plans, often going well out of their way to avoid the turbulence.

The hurricane season runs from 1 June to 30 November , though November is not included in the old mariner’s rhyme — perhaps an indication of how seasons have shifted over the years:

June too soon

July stand by

August come it must

September remember

October all over . . .

Most Atlantic hurricanes are born off Africa’s west coast in the Inter-Tropical Convergence Zone (ITCZ), in latitudes between 5 degrees and 25 degrees north of the equator, where the trade winds of the northern and southern hemispheres meet. These tropical disturbances occur when the water temperature at the surface of the ocean reaches 26.5 degrees celsius. An important factor is weak wind shear, allowing storm clouds to swell. Wind and warm water are energy which fuel a hurricane.

About 100 such tropical disturbances can form in a year. Of these, a handful will grow into tropical depressions with an organised low pressure centre. As the large area of moist air rises off the ocean, more air pushes in, and the wind movement begins to curve with the earth’s rotation. In this way the storm begins to coalesce. Trade winds carry it slowly westward, at about 12 miles an hour. The tropical depression becomes a tropical storm. When the spiralling winds reach 74 miles an hour, the pressure falls very rapidly in the air column in the centre of the storm, called the eye, and the system is categorised as a hurricane.

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The eye may be 10 to 20 miles across. The low pressure causes sea water to rise within the eye, sometimes as much as three feet. Very heavy rains come down in this low pressure area.

The life of a hurricane averages six days, but can be as long as two weeks. Some systems expire before their Atlantic crossing is complete; others continue to strengthen. Some storms hold to a westward track towards the Caribbean, but many veer north-west into the open Atlantic and miss the islands altogether. Some churn on into the Gulf of Mexico or towards the US east coast.

Just before a hurricane, the air is clear and still. As the rain begins, the wind picks up. The front edge of the storm brings powerful winds and beating rain. There is a period of calm and clear sky as the “eye” passes over, then another period of rain and strong winds, blowing in the opposite direction.

It is the wind that terrifies; witnesses have described the sound like “a freight train”, loud, constant and inexorable. But it is the water that damages: storm surges, flooding, mud slides.

Because of the immense damage a hurricane can do, plenty of warning and thorough preparation are vital, as everyone in the Caribbean knows. The World Meteorological Organisation — made up of hundreds of met offices in member states — tracks changing weather around the world, 24 hours every day, and issues timely information and warnings about tropical storms.

The National Hurricane Centre (NHC) in Miami also performs a key role in forecasting and monitoring Atlantic hurricanes. It works closely with the National Oceanic and Atmospheric Administration of the US Department of Commerce. Its website (www.nhc.noaa.gov) is the repository of almost everything that is known about hurricanes since 1492, and provides constant updates online during the hurricane season.

In some years, the number and severity of storms can be  tempered by the effects of El Niño, the warming pattern in the Pacific. When El Niño prevails, the winds from the west in the upper atmosphere over the Caribbean inhibit the formation of cloud banks, and therefore of hurricanes. But it’s not a decisive influence. In 1992, during an El Niño episode, one of the costliest storms ever, Hurricane Andrew, ravaged south Florida. Andrew was a category 4 storm; perhaps, were it not for El Niño, Andrew may have been more intense.

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From a distance, we can marvel at the power of a hurricane. But few people who have lived through one will ever forget the experience. In the Caribbean islands, certain names still evoke strong memories: Janet, Cleo, David, Flora, Hugo, Andrew, Bret, Debby, Fran. The word hurricane itself has Caribbean roots: it is an Amerindian word, passed on to the early European settlers, who had no similar experience of seasonal weather.

Hurricanes weaken and die when they encounter large land masses or colder water. But over land, they can dump torrential rainfall that causes flooding, as Mitch did when it stalled over Honduras in November 1998.

Mitch had started as a tropical wave off southern West Africa on 9 October, and moved through the eastern Caribbean ten days later. It became a hurricane on 24 October, some 255 nautical miles south-west of Jamaica. It reached the highest hurricane status (category 5) with winds of 155 knots on 26 October, and dumped heavy rain on Honduras for a week. Flash floods and mud slides washed through villages in Honduras, Nicaragua, Guatemala and El Salvador.

The sheer scale of the damage that Mitch caused put the storm in the same league as the 1900 Galveston hurricane, whose storm surge caused some 8,000 to 10,000 deaths along the Gulf coastline of Texas. These two are second only to the Great Hurricane of October 1780, which cut a swathe through the Lesser Antilles, taking as many as 20,000 lives, in the days before any sort of reliable warning was available.

On the Caribbean islands, people know how to prepare for these trials. Flooding, and destruction of reefs, beaches and forest cover are usually followed by vigorous regeneration and new growth. Like the rest of nature, humans learn to recover quickly. “We are fortunate that our tiny islands in the vast Caribbean sea are easy to miss,” says Trinidad meteorologist Glen de Souza, “though that’s no consolation for some islands that seem to be touched regularly.”

After the hurricane passes, the Caribbean sky is bluer and brighter than before. That’s when you can stand on the beach, breathe deeply and thank God for small mercies!

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Many years ago, hurricanes in the West Indies were named after saints. In 1953, the US National Weather Service began using female names. From 1979, men’s names were added. French, Spanish and English names are used, but none beginning with Q, U or Z. The World Meteorological Organisation uses six lists in rotation. If a hurricane is very deadly or costly, the name is retired forever. The names to be used in 2001 are Allison, Barry, Chantal, Dean, Erin, Felix, Gabrielle, Humberto, Iris, Jerry, Karen, Lorenzo, Michelle, Noel, Olga, Pablo, Rebekah, Sebastien, Tanya, Van, Wendy. The National Hurricane Centre expects nine or ten tropical storms this year.


A Hurricane Watch means that a hurricane may threaten within 36 hours. Hurricane Warnings are issued within the 24 hours before one is expected. Standard advice:

• Listen for latest advisories

• Leave low-lying areas and beaches

• Moor boats securely

• Secure loose outdoor objects

• Board up windows

• Store clean drinking water

• Fuel your car

• Stay at home unless officially advised to do otherwise

• Beware the eye of the storm: this lull is followed by the strongest winds

• Place important documents in a waterproof container

• Keep a list of important telephone numbers

(Courtesy NEMWIL)