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[Palm tree going down]]

Hurricanes, 1995

By Joe Strykowski

[Shoreline being eroded]
 

"Hurricane Allen-most intense hurricane in eastern Caribbean this century-a hurricane watch is in effect for southwest section of the Dominican Republic and the southwest peninsula of Haiti..."

Scholars estimate man’s total body of knowledge doubles every five years. I glare at my radio and wonder why in hell we can’t do a better job anticipating violent storms. The voice of the U.S. National Weather Service in San Juan is calm: but I am not reassured.

I love the sea...the taste and smell of its spray. But today I am flummoxed by its uncharacteristic violence. The laconic voice has warned of 300 km/hr (186 mph) winds. Anything on deck not bolted down will be carried away. My little boat reels under Allen’s brute strength and my bowels are misbehaving.

Weeks later, I will study satellite images tracing Allen’s movements. The violent winds and lashing rain encircling the hurricane’s spectacular eye give testimony to its awesome power.

"Air Force reconnaissance indicates Hurricane Allen has continued to strengthen during the evening. Central pressure is now down to 915 millibars (The lowest pressure ever recorded in the United States was 892.31 millibars, measured during a hurricane in September 1935) the center of Hurricane Allen is located near latitude 14º48N, longitude 67ºW...It is moving slightly north of due west at about 32 km/hr."

My boat secured, I race across Jamaica’s north coast. Passing one tin-roof village after another. The flimsy little houses jammed together on greasy hill-slides, await the inevitable mudslides the rains will bring.

I can’t help wondering if these shacks are any more hurricane-proof than those swept into Galveston Bay on September 8, 1900. The violence of that storm claimed 6,000 Texas lives.

"No change in speed or direction is expected during the next 24 hours. ...Highest winds are now 257 km/hr. Hurricane force winds extend outward 64 km in all directions from the center."

Landfall
The disturbed area of a well-developed hurricane is enormous. Allen’s eye was still well out to sea, when Jamaica’s north coast was being ravaged by the periphery of the storm. Hurricanes and the torrential rains they bring can cut a wide swath of destruction- flattening everything in their path. Wind speeds may reach 360 km/hr. Once a hurricane moves over land, the storm cannot sustain itself. Over the continental United States, hurricanes dissipate after one or two days. Nevertheless, hurricanes do not stand still. The storm may travel hundreds of miles in 24 hours.

Storm Surge
The hurricane’s most destructive impact is caused by the storm surge. When Hurricane Opal blazed a 120 mile long swath through Florida’s Panhandle on October 4 this year, it came ashore with 125 mph winds and a 15-foot storm surge. Considering the giant seas generated as the storm pushes toward shore, a storm surge 6 meters high would not be unusual. A researcher estimated one wave crossing the reef crest during Allen’s fury at the Discovery Bay Marine Laboratory stood 50 feet high. In 1970 when a storm surge struck the delta area of Bangladesh, the unofficial death toll ran to 500,000.

Outer fringes of severe Hurricane Allen spreading across South Texas...Tides of 5 to 7 meters near landfall area. Hurricane warnings in effect for Texas Coast...Rising tides have cut off escape routes. Sustained winds are 275 km/hr. Heavy rains will spread inland along the hurricane track...possible inland flooding.

Flooding
Hurricanes are monster rain-makers. During one Jamaican hurricane, more than 2,400 mm (93.6 inches) of rain was recorded in one four-day period. When hurricanes make their landfall coincident with a high tide, extreme property loss and estuary destruction results.

Torrential rains from decaying hurricanes often cause river flooding. Even the remnants of a storm can produce 6 to 12 inches of rain. When Hurricane Gilbert in 1988 flooded Monterrey, Mexico, the Santa Catarina River overran its banks and drowned 160 people.

Wind Damage
To be rated a major hurricane requires a wind speed of at least 200 km/hr and winds extending at least 160 km from the eye of the hurricane.

Hurricanes are Earth’s most powerful weather systems. In terms of total energy, an average hurricane produces an amount of energy equal to the total amount of electricity consumed by the United States in a six month period.

When a well-developed hurricane smashes into land the damages can run into the billions (Hurricane Andrew-August 24, 1992 left $16 billion in insured damages in its wake.) Devastating hurricanes bring long-lasting effects to landfall. Infrastructure is hobbled, and a year’s crop of sugarcane and bananas lies rotting.

Destruction of Coral Reefs
Coral reefs, exquisite and within reach of most divers, durable and timeless and yet, vulnerable to catastrophic destruction when exposed to the high energy of powerful hurricanes.

The reefs along Jamaica’s north coast are the best studied in the world. They have been decimated by several hurricanes since 1980, beginning with Hurricane Allen. A category 5 hurricane, Allen was one of the strongest hurricanes of the century. After almost four decades of fairly benign weather, Allen set in motion a decline in the vitality of Jamaica’s coral reefs. The reefs were nearly 60 percent coral dominated at that time: today they are less than 5 percent.

Physical Damage
Hurricanes are the greatest cause of large-scale mechanical destruction and mortality on coral reefs. Their passage over a reef often means destruction of large areas of corals. Entire colonies are uprooted and carried off the reef. The habitats of reef animals are ravaged and swept away.

In Jamaica, forests of elkhorn coral collapsed and broke into pieces when the water was sucked out from under them. Huge seas rolled boulder corals ashore like giant bowling balls.

Severe runoff carries enormous loads of sediment to the reef with the passage of the storm. A healthy coral reef can probably survive sediment accumulation-but when corals are already besieged they cannot survive many more insults.

Large areas of mangrove forests are uprooted or destroyed by massive sedimentation or altered salinity. When Hurricane Donna stuck Everglades National Park in 1960, it killed up to 75 percent of 100,000 acres of the parks’s mangroves.

Recovery
When visited by moderate hurricanes, where damage ashore and underwater on coral reefs is light, it is easy to project complete recovery in 25 years.

But there are hurricanes which become catastrophic storms causing topographic, sedimentological and ecological changes to the coral reefs that 100 years of recovery cannot repair.

A healthy coral reef, like a healthy rain forest, is characterized by its diversity.

A coral reef which has achieved biological stability undergoes a recovery period of larval recruitment, recolonization and coral growth which might take two or three decades. Healthy coral reefs in the past seemed to grow faster after periods of unfavorable conditions.

Competition keeps the system dynamic and competitively superior species, like algae, are kept from dominance over corals by urchins and other herbivore grazing.

But Jamaica's reefs-like most others around the world-have been badly degraded by a half-century of combined natural and human disturbances and future hurricanes are likely to depress the coral growth even more.

The Future?
This is what we know for sure: Hurricanes are occurring with greater intensity and frequency. Insurance industry figures show the number of catastrophic windstorms in the 1980's was 29. That's more than double the 14 of the 1970's. And in the 1995 hurricane season so far, we've experience more (11 with Tanya) than were produced by the entire decade of the 1960's (8).

Climatologist are baffled by the frequency and intensity of extremes of weather and climate. El Niño conditions caused by extreme warming of Pacific equatorial waters are blamed by some for the present violent weather.

Other researchers ascribe it to the start-up of the feared global warming; and still others to something as simple as a natural climate variation. A few are content to admit they just don't know.

Back in the 1970's, researchers at the University of California predicted a global warming trend through the end of the century, followed by a cold snap lasting well into the second half of the 21st century.

How cold? As much as four degrees.

Oh, that's not so bad, you might think. Well consider this: It only takes a 10 degree drop to bring on an Ice Age.

This much seems clear: Hurricanes and other wild weather patterns will likely be with us for the next sixty years. The quiet and benign weather of the past four decades is over.

[More On Hurricanes And How They Are Formed]