Hurricane Katrina

The most destructive hurricane to hit the United States in historic times was born unceremoniously as Tropical Depression Twelve over the southeastern Bahamas on August 23, 2005. By the next morning, it had become Tropical Storm Katrina, and one day later it was a hurricane. That same day, the storm moved over south Florida as a Category 1 hurricane, killing nine people and causing an estimated $600 million in damage.

But that was just Katrina's opening act. The storm traveled west over the Gulf of Mexico, where water temperatures

Air Pollutants New Orleans

Hurricane Katrina seen from above. (NASA /Jeff Schmaltz, MODIS Land Rapid Response Team)

were as high as 89°F (32°C), providing ample heat for the storm to grow into a behemoth. On August 27, Katrina was upgraded to Category 3 and within just 24 hours it reached Category 5 with maximum sustained winds of 175 mph (280 kph) and gusts of 215 mph (344 kph). As the storm lumbered through the Gulf, Ray Nagin, the mayor of New Orleans, Louisiana, ordered an unprecedented mandatory evacuation of the city.

At 1:30 a.m., Monday, August 29, Hurricane Katrina made landfall as a Category 4 hurricane with peak winds of approximately 150 mph (240 kph). Its minimum pressure of 918 millibars (mbar) made it the third strongest hurricane to strike the United States. Although the storm had been headed straight for New Orleans, it veered slightly eastward as it neared the Gulf Coast, so that the city was struck by the less powerful, western eye wall of the storm. While New Orleans was spared the most intense winds and highest storm surge, the entire Gulf Coast, including Louisiana,

Hurricane Katrina seen from above. (NASA /Jeff Schmaltz, MODIS Land Rapid Response Team)

Flooding in New Orleans in the aftermath of Hurricane Katrina. Lake Pontchartrain, at the top of the photo, is the source of the water. At the bottom, near the banks of the Mississippi River, is the relatively high ground that did not become submerged. (Lawrence Ong, EO-1 Mission Science Office, NASA, GSFC)

Mississippi, Alabama, and Florida, was damaged. The 30-foot (9 m) storm surge at Biloxi, Mississippi, was the highest ever observed in the United States, and enormous amounts of damage were done. Federal disaster declarations covered 90,000 square miles (233,000 km) of the United States, an area almost as large as the United Kingdom. Once on land and cut off from its power supply of warm ocean water, the massive storm rapidly lost strength and was downgraded to a tropical depression within 24 hours.

News reports that New Orleans had been saved from the brunt of storm damage were premature. By late morning on August 29, the storm surge collapsed several sections of the levee system that kept water out of the city. Eventually, 80% of New Orleans would be underwater. Early on, Mayor Nagin estimated that

Hurricane Katrina Death Toll

there would be as many as 10,000 dead, but this number was nothing more than a guess. The actual death toll was around 1,300 in New Orleans alone, with as many as 2,500 fatalities in all. Additionally, one million people were displaced. As of early 2007, New Orleans is still a shambles, and many of its former residents are living their lives elsewhere.

when these conditions of warmer water and low wind shear did not predominate. But even quiet periods can have major hurricanes; one of the most devastating storms in history, Hurricane Andrew, struck in 1992. However, the predicted increase in hurricanes may be countered by another predicted atmospheric change—an increase in El Niño events. The weakening or reversal in the trade winds brought about by El Niño is thought by experts to suppress the formation and intensity of hurricanes.

In the five years between 1995 and 2000, hurricanes formed at a rate twice as great as during the quiet period between 1971 and 1994, with the Caribbean experiencing a five-fold increase. During this five-year period, the frequency of storms with sustained winds of more than 100 mph (160 km/hr) was 2.5 times as high. Wind speed is significant because a storm with 130 mph (209 km/hr) winds has almost double the strength of one with 100 mph (160 km/hr) winds. Indeed, even though they account for only one-fifth of the storms that make landfall, these intense 100-mph-plus storms produce more than 80% of the damage from all hurricanes put together.

Increases in the quantity and severity of hurricanes will have different consequences for different locations. In the United States, where there are good warning and social services systems, most of the greatest storm losses will be measured in property. The six major storms that struck the United States in 2004 caused damages of about $42 billion. In 2005, the more than $100 billion price tag from Hurricane Katrina dwarfed the previous record holder, Hurricane Andrew, whose damages totaled $36 billion (adjusted for inflation). Hurricane Katrina also showed that even a developed nation is not immune to high fatalities from storms. In the Caribbean, where social services are not as well developed, the loss of life from a severe hurricane may be extreme.

Continue reading here: Extreme Heat

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  • MELBA
    What water tempature caused Katrina to grow?
    2 years ago