Hurricane Katrina was an extremely powerful and catastrophic tropical cyclone that affected the Southeastern United States in late August 2005, particularly in and around the city of New Orleans. Katrina became the United States' costliest tropical cyclone, with an estimated $125 billion ($206 billion when adjusted for inflation) in damages. The hurricane killed 1,392 people, making it the deadliest American hurricane since the 1928 Okeechobee hurricane and is the only mainland U.S. hurricane to have killed over a thousand people since then. Katrina was the twelfth tropical cyclone, the fifth hurricane, the third major hurricane, and the second Category 5 hurricane of the 2005 Atlantic hurricane season. It was also the fourth-most intense Atlantic hurricane to make landfall in the contiguous United States, as measured by barometric pressure.
The hurricane originated on August 23 near the Bahamas, from the merger of a tropical wave and the remnants of a tropical depression. Katrina strengthened into a hurricane before making its first landfall in southeast Florida on August 25. Crossing the state, the hurricane entered the Gulf of Mexico on August 26 and rapidly intensified. Early on August 28, Katrina peaked as a Category 5 hurricane, with winds of 175 mph (280 km/h) and a minimum central pressure of 902 mbar (26.64 inHg). Turning to the north, the hurricane weakened to a Category 3 hurricane before making landfall on August 29 near Buras-Triumph, Louisiana, with a subsequent final landfall near the Louisiana–Mississippi border. Katrina also produced a widespread tornado outbreak while moving inland and weakening. On August 31, a cold front over Ohio absorbed the circulation of the former hurricane. The remnants of Katrina continued to the northeast, later moving through Canada before losing their identity on September 7 over the eastern Great Lakes.
Eighty percent of New Orleans, as well as large areas in neighboring parishes, were flooded. It is estimated that about 97,000 people remained in the City of New Orleans, despite mandatory evacuation orders. The flooding prompted a massive national and international response effort, including federal, local, and private rescue operations. The largest loss of life was due to flooding caused by engineering flaws in the federally built hurricane protection system, particularly the levees around New Orleans. Investigators concluded that the U.S. Army Corps of Engineers, tasked by Congress in the Flood Control Act of 1965 to design and build the region's hurricane protection, was responsible for the breached floodwalls. Later, a federal appeals court ruled that the Army Corps, despite being responsible, could not be held financially liable due to the Flood Control Act of 1928.
The preparation and emergency response from federal, state, and local governments was widely criticized, leading to the resignation of Federal Emergency Management Agency (FEMA) director Michael D. Brown. President George W. Bush also faced criticism. However, several agencies, such as the United States Coast Guard (USCG), National Hurricane Center (NHC), and National Weather Service (NWS), were commended for their actions. The destruction and loss of life caused by the storm prompted the name Katrina to be retired by the World Meteorological Organization in April 2006.
Hurricane Katrina was an extremely powerful and catastrophic tropical cyclone that affected the Southeastern United States in late August 2005, particularly in and around the city of New Orleans. Katrina became the United States' costliest tropical cyclone, with an estimated $125 billion ($206 billion when adjusted for inflation) in damages. The hurricane killed 1,392 people, making it the deadliest American hurricane since the 1928 Okeechobee hurricane and is the only mainland U.S. hurricane to have killed over a thousand people since then. Katrina was the twelfth tropical cyclone, the fifth hurricane, the third major hurricane, and the second Category 5 hurricane of the 2005 Atlantic hurricane season. It was also the fourth-most intense Atlantic hurricane to make landfall in the contiguous United States, as measured by barometric pressure.
The hurricane originated on August 23 near the Bahamas, from the merger of a tropical wave and the remnants of a tropical depression. Katrina strengthened into a hurricane before making its first landfall in southeast Florida on August 25. Crossing the state, the hurricane entered the Gulf of Mexico on August 26 and rapidly intensified. Early on August 28, Katrina peaked as a Category 5 hurricane, with winds of 175 mph (280 km/h) and a minimum central pressure of 902 mbar (26.64 inHg). Turning to the north, the hurricane weakened to a Category 3 hurricane before making landfall on August 29 near Buras-Triumph, Louisiana, with a subsequent final landfall near the Louisiana–Mississippi border. Katrina also produced a widespread tornado outbreak while moving inland and weakening. On August 31, a cold front over Ohio absorbed the circulation of the former hurricane. The remnants of Katrina continued to the northeast, later moving through Canada before losing their identity on September 7 over the eastern Great Lakes.
Eighty percent of New Orleans, as well as large areas in neighboring parishes, were flooded. It is estimated that about 97,000 people remained in the City of New Orleans, despite mandatory evacuation orders. The flooding prompted a massive national and international response effort, including federal, local, and private rescue operations. The largest loss of life was due to flooding caused by engineering flaws in the federally built hurricane protection system, particularly the levees around New Orleans. Investigators concluded that the U.S. Army Corps of Engineers, tasked by Congress in the Flood Control Act of 1965 to design and build the region's hurricane protection, was responsible for the breached floodwalls. Later, a federal appeals court ruled that the Army Corps, despite being responsible, could not be held financially liable due to the Flood Control Act of 1928.
The preparation and emergency response from federal, state, and local governments was widely criticized, leading to the resignation of Federal Emergency Management Agency (FEMA) director Michael D. Brown. President George W. Bush also faced criticism. However, several agencies, such as the United States Coast Guard (USCG), National Hurricane Center (NHC), and National Weather Service (NWS), were commended for their actions. The destruction and loss of life caused by the storm prompted the name Katrina to be retired by the World Meteorological Organization in April 2006.
Meteorological history
On August 19, 2005, a weak tropical wave combined with the mid-level remnants of Tropical Depression Ten and an upper tropospheric trough near the Lesser Antilles. On August 23, this disturbance organized into Tropical Depression Twelve over the southeastern Bahamas. The storm strengthened into Tropical Storm Katrina on the morning of August 24. The tropical storm moved towards Florida and became a hurricane only two hours before making landfall between Hallandale Beach and Aventura on the morning of August 25. The storm weakened over land, but it regained hurricane status about one hour after entering the Gulf of Mexico, and it continued strengthening over open waters. On August 27, the storm reached Category 3 intensity on the Saffir–Simpson hurricane wind scale, becoming the third major hurricane of the season. An eyewall replacement cycle disrupted the intensification but caused the storm to nearly double in size. Thereafter, Katrina rapidly intensified over the "unusually warm" waters of the Loop Current, from a Category 3 hurricane to a Category 5 hurricane in just nine hours.
After attaining Category 5 hurricane status on the morning of August 28, Katrina reached its peak strength at 1800 UTC, with maximum sustained winds of 175 mph (280 km/h) and a minimum central pressure of 902 mbar (26.64 inHg). The pressure measurement made Katrina the fifth most intense Atlantic hurricane on record at the time, only to be surpassed by Hurricanes Rita and Wilma later in the season; it was also the strongest hurricane ever recorded in the Gulf of Mexico at the time, before Rita broke the record. The hurricane subsequently weakened due to another eyewall replacement cycle, and Katrina made its second landfall at 1110 UTC on August 29, as a high-end Category 3 hurricane with sustained winds of 125 mph (201 km/h), near Buras-Triumph, Louisiana. At landfall, hurricane-force winds extended outward 120 miles (190 km) from the center and the storm's central pressure was 920 mbar (27 inHg). After moving over southeastern Louisiana and then Breton Sound, it made its third and final landfall near the Louisiana–Mississippi border, with Category 3 sustained winds of 120 mph (195 km/h). Katrina maintained hurricane strength well into Mississippi, finally weakening to tropical storm strength more than 150 miles (240 km) inland near Meridian, Mississippi. It was downgraded to a tropical depression near Clarksville, Tennessee; its remnants were absorbed by a cold front in the eastern Great Lakes region on August 31. The resulting extratropical storm moved rapidly to the northeast and affected eastern Canada and was absorbed within a frontal zone over the eastern Great Lakes.
Preparations
Federal government
The United States Coast Guard began pre-positioning resources in a ring around the expected impact zone and activated more than 400 reservists. On August 27, it moved its personnel out of the New Orleans region prior to the mandatory evacuation. Aircrews from the Aviation Training Center, in Mobile, staged rescue aircraft from Texas to Florida. All aircraft were returning towards the Gulf of Mexico by the afternoon of August 29.
President George W. Bush declared a state of emergency in selected regions of Louisiana, Alabama, and Mississippi on August 27. On Sunday August 28, Governor Kathleen Blanco requested that the President declare an "expedited major disaster for the State of Louisiana" including all the southeastern parishes including the City of New Orleans. On Sunday, August 28, President Bush spoke with Governor Blanco to encourage her to order a mandatory evacuation of New Orleans."
The Associated Press reported that federal officials warned President Bush before landfall that Katrina could 'breach levees', however the AP subsequently corrected that characterization, namely that the pre-landfall federal briefing warned about 'overtopping' not structural breach/failure. The first suggestion that levees could fail structurally occurred at 1:47 a.m. August 29 in a memo from the Homeland Security Operations Center to the White House Situation Room, nine hours after the evacuation was already completed.
Data provided by FEMA indicate that over 1.2 million people along the northern Gulf coast from southeastern Louisiana to Alabama were under some type of evacuation order.
National Hurricane Center (NHC)
The NHC issued 31 bulletins between August 23 and August 30. Late on the afternoon of Friday August 26, the Center's prediction models shifted in unison away from the Florida panhandle, and New Orleans was moved to the center of the cone of certainty. Jonathan Erdman, senior meteorologist at Weather.com called this “one of the two most memorable forecast shifts I've seen in my 28-plus year career in meteorology, along with Sandy.” At 10:00 a.m. CDT on Sunday August 28, the NHC issued a bulletin predicting maximum sustained winds of 175 mph (280 km/h) and urging that "preparations to protect life and property should be rushed to completion. At 10:11 a.m CDT, Robert Ricks in the Slidell office of the NWSre-issued the bulletin predicting that "high rise office and apartment buildings will sway dangerously... a few to the point of total collapse. All windows will blow out." In a noon teleconference on Sunday August 28, NHC Director Max Mayfield said, "on the forecast track, if it maintains intensity, about twelve feet of storm surge in the lake, the big question is will that top some of the levees? ... I don't think any model can tell you with any confidence right now whether the levees will be topped or not, but that's obviously a very, very grave concern."
State government
Florida
In Florida, Governor Jeb Bush declared a state of emergency on August 24 in advance of Hurricane Katrina's landfall. By the following day, Florida's Emergency Operations Center was activated in Tallahassee to monitor the progress of the hurricane. Before Katrina moved ashore, schools and businesses were closed in the Miami area. Cruise ships altered their paths due to seaports in southeastern Florida closing. Officials in Miami-Dade County advised residents in mobile homes or with special needs to evacuate. To the north in Broward County, residents east of the Intracoastal Waterway or in mobile homes were advised to leave their homes. Evacuation orders were issued for offshore islands in Palm Beach County, and for residents in mobile homes south of Lantana Road. Additionally, a mandatory evacuation was ordered for vulnerable housing in Martin County. Shelters were opened across the region. Officials closed the Miami International Airport, Fort Lauderdale–Hollywood International Airport, Key West International Airport, and Florida Keys Marathon Airport due to the storm. In Monroe and Collier counties, schools were closed, and a shelter was opened in Immokalee.
Alabama
On August 28, Alabama Governor Bob Riley declared a state of emergency for the approaching Hurricane Katrina. On the same day, he requested President Bush to declare "expedited major disaster declaration" for six counties of South Alabama, which was quickly approved. Three hundred fifty national guardsmen were called on duty by August 30. The state of Mississippi activated its National Guard on August 26 in preparation for the storm's landfall. Additionally, the state government activated its Emergency Operations Center the next day, and local governments began issuing evacuation orders. By 6:00 p.m. CDT on August 28, 11 counties and cities issued evacuation orders, a number which increased to 41 counties and 61 cities by the following morning. Moreover, 57 emergency shelters were established on coastal communities, with 31 additional shelters available to open if needed.
By Sunday, August 28, most infrastructure along the Gulf Coast had been shut down, including all freight and Amtrak rail traffic into the evacuation areas as well as the Waterford Nuclear Generating Station. Since Hurricane Katrina, Amtrak's Sunset Limited service has never been restored past New Orleans.
Louisiana
By August 26, many of the computer models had shifted the potential path of Katrina 150 miles (240 km) westward from the Florida Panhandle, putting southeast Louisiana and Mississippi near the center of their track probabilities; the chances of a direct hit were forecast at 17%, with strike probability rising to 29% by August 28. Emergency management officials in New Orleans feared that the storm surge could go over the tops of levees protecting the city.
Louisiana's hurricane evacuation plan used contraflow: turning all lanes of Interstate-10 into one-way lanes outbound from the city. The concept is simple, but it requires perfect coordination local parish governments and the state police in three phases, starting with the immediate coast 50 hours before the start of tropical-storm-force winds. Persons in areas designated Phase II begin evacuating 40 hours before the onset of tropical storm winds and those in Phase III areas (including New Orleans) evacuate 30 hours before the start of such winds. Governor Blanco initiated contraflow at 4 p.m on Saturday, August 27 and ended it at 5 p.m. on Sunday, August 28. The contraflow plan successfully evacuated about one million people and is considered the most successful rapid evacuation of a major city in American history. Louisiana's Emergency Operations Plan Supplement 1C (Part II, Section II, Paragraph D) calls for use of school and other public buses in evacuations. Although buses that later flooded were available to transport those dependent on public transportation, that option was not employed. Public officials instead directed transit-dependent residents to local emergency shelters, since that strategy had worked successfully during previous hurricanes. Some estimates claimed that 80% of the 1.3 million residents of the greater New Orleans metropolitan area evacuated. The Louisiana National Guard delivered three truckloads of water and seven truckloads of MREs — short for "meals ready to eat."
Local government
New Orleans
On Sunday August 28th, at about 9:30 a.m. CDT, Mayor Ray Nagin began a news conference where he ordered the first-ever mandatory evacuation of the city, calling Katrina "a storm that most of us have long feared". The mayor also announced that the Louisiana Superdome would be "refuge of last resort" for citizens who could not leave the city. NOAA's official Katrina Service Assessment (2006) states that approximately 80% of New Orleans residents evacuated before Katrina. Using the city's approximately 485,000 residents, that implies roughly 97,000 remained.
Impact
Katrina brought hurricane conditions to southeastern Louisiana, southern Mississippi and southwestern Alabama. Storm surge flooding of 25 to 28 feet above normal tide level occurred along portions of the Mississippi coast. Almost half the total economic loss is the result of flooding in New Orleans where storm surge triggered multiple breaches in the federal flood protection. Katrina is the most costly tropical cyclone in the history of the United States with total damage estimated at $125 billion (2005 U.S. dollars). Katrina was the deadliest storm to strike the U.S. since the 1928 Okeechobee hurricane with a death toll that far outweighs any other storm during the modern era of weather forecasting.
Federal disaster declarations covered 90,000 square miles (230,000 km2) of the United States, an area almost as large as the United Kingdom. The hurricane left an estimated three million people without electricity. On September 3, 2005, Homeland Security Secretary Michael Chertoff described the aftermath of Hurricane Katrina as "probably the worst catastrophe or set of catastrophes" in the country's history, referring to the hurricane itself plus the flooding of New Orleans.