Hurricane Katrina Smashes Gulf Coast

Willie Drye
for National Geographic News

August 29, 2005

Photo Gallery: Hurricane Katrina >>

Hurricane Katrina—a nightmare of a hurricane with 140-mile-an-hour (225-kilometer-an-hour) winds and a storm surge nearly two stories tall—came ashore early this morning at the mouth of the Mississippi River near New Orleans.

Katrina is the hurricane that emergency-management and government officials have long feared would strike New Orleans. Many of the Louisiana city's 500,000 residents live below sea level and are surrounded by the waters of the Mississippi River, Lake Pontchartrain, and several bays.

"This is a biggie," said Steve Rinard, meteorologist in charge of the National Weather Service office in Lake Charles, Louisiana. "We've been dreading a storm like this."

Hundreds of thousands of Gulf Coast residents evacuated on Saturday and Sunday as the forecasts for Hurricane Katrina became more ominous. "All kinds of evacuations are going on, and shelters are filling up," Rinard said Sunday night. "There are shelters as far away as southeast Texas and all over central Louisiana."

A.J. Holloway, mayor of Biloxi, Mississippi, said Sunday night that most residents in the lowest-lying sections of his city of 55,000 had evacuated. "We don't know what to expect," Holloway said.

Category Four Storm

Hurricane Katrina made landfall as a Category Four storm on the Saffir-Simpson scale, which ranks hurricanes from one to five according to wind speeds and destructive potential.

A Category Four hurricane has winds from 131 to 155 miles an hour (211 to 249 kilometers an hour) and is capable of doing massive damage. The last Category Four hurricane to strike the U.S. was Hurricane Charley, which came ashore at Punta Gorda, Florida, in August 2004.

Hurricane Katrina began as a tropical depression just west of the Bahamas on August 23 and began slowly strengthening as it approached South Florida. The storm made landfall at Fort Lauderdale Thursday as a Category One hurricane with winds of about 80 miles an hour (129 kilometers an hour). Nine people in Florida died during the storm.

The storm made an unexpected jog southward as it crossed the Florida peninsula. Katrina emerged near the southwestern tip of the peninsula and began rapidly strengthening in the Gulf of Mexico.

Residents in the Florida Keys, which lie to the south of the peninsula, were caught off guard by Katrina's intensification.

"We went to bed [Thursday] night expecting some possible rain and woke up [Friday] morning to learn that Katrina was 75 miles [121 kilometers] north of Marathon and would creep even closer to Key West by mid-afternoon," said Dan Gallagher, a resident of Grassy Key, about 60 miles [97 kilometers] northeast of Key West.

"There was a tornado in Marathon [that] took out three airplanes in their steel hangers, and a few people lost porches."

Katrina continued to gain strength as it followed a ragged S-shaped path across the very warm waters of the Gulf of Mexico.

Fearing the Worst

Hurricanes draw their strength from warm water, and by Friday afternoon some meteorologists feared the worst—that the storm would rapidly intensify as it drew nearer to large Gulf Coast cities such as Mobile, Alabama, and New Orleans.

The Gulf Coast has been especially hard-hit by hurricanes in the past year, starting with Hurricane Charley. Powerful Hurricane Ivan devastated Pensacola, Florida, in September 2004, and Hurricane Dennis came ashore just east of Pensacola last month.

Hurricane Katrina quickly intensified during the weekend, making the jump from Category Four to Category Five in only about six hours early Saturday morning.

As Katrina took aim at the Louisiana coast Sunday, the hurricane became one of the most powerful storms to ever form in the Atlantic Ocean, with peak winds of 175 miles an hour (282 kilometers an hour). But the storm lost some of its power as it drew closer to the coast.

Emergency management officials have long feared that a powerful storm like Katrina would come ashore in an area such as New Orleans or the Florida Keys, which are especially vulnerable to hurricanes.

On June 29, Max Mayfield, director of the National Hurricane Center's Tropical Prediction Center, told a congressional subcommittee on disaster prevention and prediction that the U.S. is "more vulnerable to a hurricane catastrophe today than at any time in our nation's history."

The reason for the vulnerability is the rapid population growth on the coast during the past three decades. More than half of the U.S. population now lives in coastal areas, Mayfield said.

The population growth, coupled with a decadelong trend of active hurricane seasons, has created a potential for disaster, Mayfield said. "There have been more hurricanes during the past ten years than in any other ten-year period since (record keeping) began in 1851," he said.

The trend of active hurricane seasons is expected to continue for another 10 to 20 years.

In the past, the United States' worst hurricane disasters have occurred when a storm has rapidly intensified shortly before making landfall. That's what happened on September 2, 1935, when the most powerful hurricane in U.S. history struck the Florida Keys.

In only about 30 hours, that unnamed hurricane exploded from a tropical storm to a Category Five hurricane with winds of perhaps 200 miles an hour (322 kilometers an hour).

Hurricane Andrew, the Category Five storm that struck just south of Miami in August 1992, also blew up from a tropical storm to a monster hurricane just before coming ashore.

Hurricane Forecasts

Weather satellites, Doppler radar, and other technological innovations now allow meteorologists to closely monitor a hurricane's development and path.

But researchers are still trying to crack a key mystery about the powerful summer storms—how to predict whether a hurricane will quickly intensify from a windy thunderstorm into a screaming killer.

Forecasters now use two types of computer models to make their predictions about hurricanes—statistical models and numerical models.

Statistical models use data from past storms to predict what a current hurricane is likely to do. Numerical models take into account only data from the existing storm to make a prediction.

Numerical models generally are more accurate than statistical models but require large amounts of up-to-the-moment data to make their calculations. U.S. National Oceanic and Atmospheric Agency (NOAA) scientists are working on a numerical model to improve the accuracy of hurricane-intensification forecasts.

John Kaplan, a research meteorologist with the National Hurricane Center, said the objective of the research is to improve the performance of the numerical models. A major problem with the existing computer models is that they can't make use of all the data that's available about a developing storm.

"The data are ahead of the computer models now," Kaplan said. "We can't plug the data into the computers fast enough."

Meteorologist Naomi Surgi is leading the work to improve intensity forecasting at NOAA's Environmental Modeling Center in Camp Springs, Maryland. She said the new computer model to predict hurricane intensification will be operational in 2007.

Willie Drye is the author of Storm of the Century: The Labor Day Hurricane of 1935, published by National Geographic Books.