Gustav bears down on U.S. East Coast: the Hurricane Scenario: Gustav, an intense Cat 4 storm, wreaks supreme havoc upon the Eastern Seaboard, leaving a trail of losses from Key West to Cape Cod

The Hypothetical Scenario:

Early in the fall, the National Hurricane Center satellites identify a tropical depression in the middle of the Atlantic Ocean, moving west from the coast of West Africa. As the depression gains strength over warm water, it grows into a tropical storm. NHC calls the storm Gustav. It is the seventh tropical cyclone to emerge that year in the North Atlantic basin. NHC experts monitor it over a week as it develops into an intense hurricane that sends a glancing blow at Barbuda before heading toward the Bahamas.

Projections show that it is likely to make landfall along the east coast of Florida in Palm Beach County. With sustained winds of 145 mph, Gustav is a Saffir-Simpson Category Four storm. With landfall two days away, a hurricane warning is issued along the southeastern coast of Florida from north of Miami to Cape Canaveral. The tropical storm warning covers a broader area, from Key West to Jacksonville.

As the hurricane nears the coast, do-it-yourself and hardware stores sell out of materials and tools as residents and building owners install shutters or attempt to board-up windows. Tens of thousands of people evacuate coastal communities in the likely path of the hurricane and move inland.

As time passes, Palm Beach County and its surroundings are almost deserted. Only emergency personnel remain; a few stubborn residents and journalists are left behind. Risk managers and emergency officials are preparing for the worst. The Nuclear Regulatory Commission's Region II office in Atlanta implements its hurricane response procedure and shuts down a plant in St. Lucie. Other plants are on high alert. Utility companies activate their emergency plans.

Forecasters use reconnaissance planes, eyewitness accounts, satellite imagery and an ensemble of atmospheric models to forecast where the storm will make landfall. The latest forecasts suggest that the storm will move inland at approximately the same location as the "Great Lake Okeechobee" hurricane of September 1928, a Category Four hurricane that hit the coast near Palm Beach with sustained winds of 128 mph. At the time of Gustav's landfall, maximum gusts of 160 mph are observed in some coastal areas within the eye wall. Intense rain is reported and several tornadoes have been spotted. Gusts of 80 to 90 mph are reported in the Miami metropolitan area, about 60 miles south of where the hurricane came ashore. Heavy surf and surge affect the coastline over more than a hundred miles. Surge heights reach 15 feet over a 20-mile coastal stretch near Juno Beach, about 25 miles north of where Gustav made landfall. Florida's governor asks the President to declare Florida a major disaster area.

Once on land, Gustav weakens and begins to swing toward the north and northeast, ensuring that the highest winds remain over the heavily populated coastal communities. Gustav is quickly downgraded. Seven hours after landfall it is a tropical storm generating gusts of 80 to 90 mph at Cape Canaveral and 50 to 60 mph by the time it reaches Georgia, whereupon the storm moves back offshore. Its path is similar to the 1928 storm but as it remains closer to the coast, the high winds affect more of the coastal areas.

In the regular NHC forecasts, tropical warnings are now extended along the entire Eastern Seaboard, as the storm moves up the coast toward the Northeast.

With Gustav once again over water for about six hours, it strengthens and speeds up as it skims the coast before making landfall in South Carolina with sustained winds of 60 to 70 mph.

The storm moves north and becomes an "extra-tropical" storm as it moves along the Eastern sea board with gusts reaching 50 to 60 mph in coastal areas as far herd1 as Massachusetts over the next two days.

The storm left an impact on much of Florida's eastern coast. The most damage took place along 100 miles of coastline, between Pompano Beach and Port St Lucie. The most severe damage is reported in coastal communities. In some areas the coastal landscape has changed completely. Beach houses have been uprooted from their foundations and debris is floating in the streets, swept in by heavy surf. Many older buildings that were not built in accordance with current state and local building codes are destroyed or heavily damaged. Resorts along the coast suffer extensive damage. Several lose their beach access.

Gustav affects more than seven million Florida residents. More than 1,000 coastal structures have lost 50 percent of their market value, victims of pounding surf. Thousands of other properties suffer minor to moderate damage. In all, about one million homes, condos and apartment buildings are affected by the storm, 400,000 of them severely. In addition, 200,000 commercial properties are damaged by the storm.

POWER FAILURES

Power outages are reported over large areas of Florida where high winds topple trees and branches knock out transmission and distribution lines. More than three million customers are without power for as long as three days. Some residents have to wait several weeks before power is restored. Businesses suffer the brunt of these power outages as inventory perishes or is simply destroyed. Fortunately, only a few hospitals and fire stations suffer extensive damage.

Despite heavy rains--more than 10 inches of rain over 24 hours--and high winds, the dikes built around Lake Okeechobee after the 1928 hurricane hold. There is no catastrophic inland flooding to speak of. States north of Florida suffer damage, mainly due to heavy rains and gusty winds, which knock down trees and inflict property damage. One million residents are affected in these states, including many hl Rhode Island and Massachusetts where 300,000 buildings suffer mostly minor damage. While improved tree-clearance since 2003's Hurricane Isabel has reduced the impact of power outages in the Carolinas and the Mid-Atlantic states, several million people are without power in New England.

Building damage and flying debris from Gustav are directly responsible for 25 deaths, while another 60 fatalities are linked to the hurricane. The number of casualties is much lower than in the 1928 storm, in which more than 1,800 people died. Total U.S. economic losses reach an estimated $75 billion, with 95 percent of the losses occurring in Florida.

Total private insurance claims are reported to be about $48 billion, with insurance companies on the hook for about $45 billion of that $48 billion. Roughly two-thirds of those claims reflect residential losses; the large majority being wind-related. About $500 million in flood losses is paid out to businesses covered by flood insurance. Residential, coastal and inland flood losses are reported to be on the order of $1 billion, the majority of which are covered by the federal flood insurance program. Emergency and clean-up costs are estimated to be about $2 billion. Losses to agriculture are several billions of dollars, part of it covered by insurance.

Losses from Hypothetical Hurricane Gustav

            Typs of Loss                Total Loss     Insured Losses

Property and infrastructure damage      $57 billion     $37 billion
Workers' compensation, life and
  health costs                          $100 million    $50 million
Direct costs of business interruption   $15.5 billion   $8 billion
Other costs (e.g. emergency response)   $2 billion      --

Total Direct Costs:                     $74.6 billion   $45.1 billion

Total number of people killed:                85
Total hospitalized with serious
  injuries:                                  150
Total treated at outpatient clinics:         500

Source: Risk Management Solutions

RELATED ARTICLE: Mother nature's deadly spins.

Virtually every coastal area along the Gulf and eastern coasts of the United States, along with Hawaii, have the potential to be struck by a hurricane but some coastal areas are more at risk than others. The patterns of hurricane activity can be observed from history and explained by the physics and climatology of hurricane formation and motion. In an average year, three tropical storms hit the continental United States. About two of every three of these tropical storms come ashore with hurricane strength.

Loss reconstructions show that 80 percent of all historical hurricane losses resulted from just 65 hurricanes-a relatively small proportion of all hurricanes to hit the United States.

Since the devastating hurricane that battered Galveston in 1900 and claimed more than 8,000 lives, major investments have been made in better preparedness, and improved methods of tracking and forecasting hurricanes. As a result there are today far fewer deaths from hurricanes, despite a dramatic increase in the number of people living along the coasts. Between 1900 and 1960, 12 hurricanes caused more than 200 deaths each. Since the 1960s, the average number of people who die every year from hurricanes is 25.

Economic losses due to hurricanes, however, have increased steadily as more people choose to live by the shore.

The highest historical reconstructed losses (modeled with current exposures and values) in the past 100 years would come from a Category Four hurricane that hit Miami in 1926, causing $87 billion in damages and $47 billion in insured losses. The Category Three hurricane that hit New England in 1938 would cause $28 billion in damages and $17 billion in insured losses. The small but intense Category Five, Hurricane Andrew, in 1992 would cause $38 billion in damages and $23 billion in insured losses.

About 80 percent of U.S. coastal residents from Texas to Maine have not experienced a direct hit from a major hurricane since 1900. Risk Management Solutions first developed a catastrophe model for hurricane loss in 1993 and has revised this model over subsequent years. The model simulates tens of thousands of hurricanes that represent the frequency and severity of hurricanes likely to cause significant loss in the United States.

This model shows that there is a 1 percent annual probability that a direct economic loss of $75 billion or more could occur somewhere in the United States from the occurrence of an hurricane--i.e, a $75 billion economic loss has a 100-year "return period."

Results obtained with such a model show that there is a wide range of simulated hurricanes that could give such losses with 1 percent annual probability.

Gustav is a hypothetical scenario. This storm is similar to the "Great Lake Okeechobee" hurricane of September 1928. While the track and the impacts are different, Gustav illustrates the impacts of one of the many intense hurricanes that could strike this region.

Most of the economic losses resulting from Gustav are due to wind and wind-related perils. Surge and rainfall perils contributed to a relatively small portion of the total economic losses. This might not be true for other areas such as New York, for example, where the funneling coastline makes the region more vulnerable to coastal storm surge.

Gustav is by no means a worst-case hurricane scenario. Hurricanes with the same intensity could make a direct hit on a large metropolitan area, such as Miami, which would, in turn, have resulted in larger losses. Intense surge and flooding could have an impact on protective flood structures, such as in New Orleans, leading to widespread urban flooding. It would even be possible for Miami and New Orleans to be hit by the same hurricane in the space of two days. This almost happened in 1992.

--Auguste Boissonnade

AUGUSTE BOISSONNADE, PHD., was the original architect of the Risk Management Solutions' hurricane catastrophe models. He is a member of the American Meteorological Society and the American Society of Civil Engineers

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