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152-458: Hurricane Katrina was a powerful and devastating tropical cyclone that caused 1,392 fatalities and damages estimated at $ 125 billion in late August 2005, particularly in the city of New Orleans and its surrounding area. It is tied with Hurricane Harvey as being the costliest tropical cyclone in the Atlantic basin . Katrina was the twelfth tropical cyclone, the fifth hurricane, and

304-531: A Tropical Cyclone Warning Centre by the World Meteorological Organization 's (WMO) tropical cyclone programme. These warning centers issue advisories which provide basic information and cover a systems present, forecast position, movement and intensity, in their designated areas of responsibility. Meteorological services around the world are generally responsible for issuing warnings for their own country. There are exceptions, as

456-431: A low-pressure center, a closed low-level atmospheric circulation , strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls . Depending on its location and strength, a tropical cyclone is called a hurricane ( / ˈ h ʌr ɪ k ən , - k eɪ n / ), typhoon ( / t aɪ ˈ f uː n / ), tropical storm , cyclonic storm , tropical depression , or simply cyclone . A hurricane

608-416: A 1.5 degree warming lead to "increased proportion of and peak wind speeds of intense tropical cyclones". We can say with medium confidence that regional impacts of further warming include more intense tropical cyclones and/or extratropical storms. Climate change can affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in

760-444: A 2019 review paper show a future increase of rainfall rates. Additional sea level rise will increase storm surge levels. It is plausible that extreme wind waves see an increase as a consequence of changes in tropical cyclones, further exacerbating storm surge dangers to coastal communities. The compounding effects from floods, storm surge, and terrestrial flooding (rivers) are projected to increase due to global warming . There

912-549: A bottleneck at the Rigolets Pass, forcing it farther inland. The range of surge levels in eastern St. Tammany Parish is estimated at 13–16 feet (4.0–4.9 m), not including wave action. Hard-hit St. Bernard Parish was flooded because of breaching of the levees that contained a navigation channel called the Mississippi River Gulf Outlet (MR-GO) and the breach of the 40 Arpent canal levee that

1064-613: A circle, whirling round their central clear eye , with their surface winds blowing counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere . The opposite direction of circulation is due to the Coriolis effect . Tropical cyclones tend to develop during the summer, but have been noted in nearly every month in most tropical cyclone basins . Tropical cyclones on either side of

1216-405: A flow of warm, moist, rapidly rising air, which starts to rotate cyclonically as it interacts with the rotation of the earth. Several factors are required for these thunderstorms to develop further, including sea surface temperatures of around 27 °C (81 °F) and low vertical wind shear surrounding the system, atmospheric instability, high humidity in the lower to middle levels of

1368-506: A higher intensity. Most tropical cyclones that experience rapid intensification are traversing regions of high ocean heat content rather than lower values. High ocean heat content values can help to offset the oceanic cooling caused by the passage of a tropical cyclone, limiting the effect this cooling has on the storm. Faster-moving systems are able to intensify to higher intensities with lower ocean heat content values. Slower-moving systems require higher values of ocean heat content to achieve

1520-622: A hurricane. After briefly weakening to tropical storm strength over southern Florida, Katrina entered the Gulf of Mexico on August 26 and rapidly intensified . The storm strengthened into a Category 5 hurricane over the warm waters of the Gulf of Mexico before weakening to a high-end Category 3 hurricane at its second landfall on August 29 over southeast Louisiana and Mississippi . The largest loss of life in Hurricane Katrina

1672-464: A large number of forecasting centers, uses infrared geostationary satellite imagery and an algorithm based upon the Dvorak technique to assess the intensity of tropical cyclones. The ADT has a number of differences from the conventional Dvorak technique, including changes to intensity constraint rules and the usage of microwave imagery to base a system's intensity upon its internal structure, which prevents

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1824-464: A large role in both the classification of a tropical cyclone and the determination of its intensity. Used in warning centers, the method was developed by Vernon Dvorak in the 1970s, and uses both visible and infrared satellite imagery in the assessment of tropical cyclone intensity. The Dvorak technique uses a scale of "T-numbers", scaling in increments of 0.5 from T1.0 to T8.0. Each T-number has an intensity assigned to it, with larger T-numbers indicating

1976-656: 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 . On August 28, Alabama Governor Bob Riley declared

2128-436: A massive national and international response effort, including federal, local, and private rescue operations to evacuate those displaced from the city in the following weeks. After the storm, multiple investigations concluded that the U.S. Army Corps of Engineers , which had designed and built the region's levees decades earlier, was responsible for the failure of the flood-control systems. However, federal courts later ruled that

2280-426: A much smaller area. This replenishing of moisture-bearing air after rain may cause multi-hour or multi-day extremely heavy rain up to 40 km (25 mi) from the coastline, far beyond the amount of water that the local atmosphere holds at any one time. This in turn can lead to river flooding , overland flooding, and a general overwhelming of local water control structures across a large area. A tropical cyclone

2432-493: A number of techniques considered to try to artificially modify tropical cyclones. These techniques have included using nuclear weapons , cooling the ocean with icebergs, blowing the storm away from land with giant fans, and seeding selected storms with dry ice or silver iodide . These techniques, however, fail to appreciate the duration, intensity, power or size of tropical cyclones. A variety of methods or techniques, including surface, satellite, and aerial, are used to assess

2584-522: A peninsula between the Back Bay and the coast, was particularly hard hit, especially the low-lying Point Cadet area. In Jackson County, storm surge flowed up the wide river estuary , with the combined surge and freshwater flooding cutting the county in half. Remarkably, over 90% of Pascagoula, the easternmost coastal city in Mississippi, and about 75 miles (120 km) east of Katrina's landfall near

2736-422: A process known as rapid intensification, a period in which the maximum sustained winds of a tropical cyclone increase by 30  kn (56 km/h; 35 mph) or more within 24 hours. Similarly, rapid deepening in tropical cyclones is defined as a minimum sea surface pressure decrease of 1.75 hPa (0.052 inHg) per hour or 42 hPa (1.2 inHg) within a 24-hour period; explosive deepening occurs when

2888-429: A remnant low-pressure area . Remnant systems may persist for several days before losing their identity. This dissipation mechanism is most common in the eastern North Pacific. Weakening or dissipation can also occur if a storm experiences vertical wind shear which causes the convection and heat engine to move away from the center. This normally ceases the development of a tropical cyclone. In addition, its interaction with

3040-477: A result of Hurricane Katrina and two people died in a traffic accident in the state. Residents in some areas, such as Selma, were without power for several days. Northern and central Georgia were affected by heavy rains and strong winds from Hurricane Katrina as the storm moved inland, with more than 3 inches (76 mm) of rain falling in several areas. At least 18 tornadoes formed in Georgia on August 29, 2005,

3192-496: A result of Hurricane Katrina. Katrina's storm surge inundated all parishes surrounding Lake Pontchartrain, including St. Tammany , Tangipahoa, St. John the Baptist , and St. Charles Parishes. St. Tammany Parish received a two-part storm surge. The first surge came as Lake Pontchartrain rose and the storm blew water from the Gulf of Mexico into the lake. The second came as the eye of Katrina passed, westerly winds pushed water into

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3344-414: 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,

3496-509: A state of emergency in selected regions of Louisiana, Alabama, and Mississippi on August 27. "On Sunday, August 28, President Bush spoke with Governor Blanco to encourage her to order a mandatory evacuation of New Orleans." However, during the testimony by former Federal Emergency Management Agency (FEMA) chief Michael Brown before a U.S. House subcommittee on September 26, Representative Stephen Buyer (R-IN) inquired as to why Bush's declaration of state of emergency of August 27 had not included

3648-569: A storm. Tropical cyclone scales , such as the Saffir-Simpson hurricane wind scale and Australia's scale (Bureau of Meteorology), only use wind speed for determining the category of a storm. The most intense storm on record is Typhoon Tip in the northwestern Pacific Ocean in 1979, which reached a minimum pressure of 870  hPa (26  inHg ) and maximum sustained wind speeds of 165 kn (85 m/s; 305 km/h; 190 mph). The highest maximum sustained wind speed ever recorded

3800-630: A strong Category 3 hurricane. Although the storm surge to the east of the path of the eye in Mississippi was higher, a significant surge affected the Louisiana coast. The height of the surge is uncertain because of a lack of data, although a tide gauge in Plaquemines Parish indicated a storm tide in excess of 14 feet (4.3 m), and a 12-foot (3.7 m) storm surge was recorded in Grand Isle . The hurricane made its final landfall near

3952-581: A stronger system. Tropical cyclones are assessed by forecasters according to an array of patterns, including curved banding features , shear, central dense overcast, and eye, to determine the T-number and thus assess the intensity of the storm. The Cooperative Institute for Meteorological Satellite Studies works to develop and improve automated satellite methods, such as the Advanced Dvorak Technique (ADT) and SATCON. The ADT, used by

4104-405: A system has dissipated or lost its tropical characteristics, its remnants could regenerate a tropical cyclone if environmental conditions become favorable. A tropical cyclone can dissipate when it moves over waters significantly cooler than 26.5 °C (79.7 °F). This will deprive the storm of such tropical characteristics as a warm core with thunderstorms near the center, so that it becomes

4256-529: A traffic accident. Eastern Arkansas received light rain from the passage of Katrina. Gusty winds downed some trees and power lines, though damage was minimal. Katrina also caused a number of power outages in many areas, with over 100,000 customers affected in Tennessee , primarily in the Memphis and Nashville areas. Tropical cyclone A tropical cyclone is a rapidly rotating storm system with

4408-529: A tropical cyclone are a result of the conservation of angular momentum imparted by the Earth's rotation as air flows inwards toward the axis of rotation. As a result, cyclones rarely form within 5° of the equator . Tropical cyclones are very rare in the South Atlantic (although occasional examples do occur ) due to consistently strong wind shear and a weak Intertropical Convergence Zone . In contrast,

4560-461: A tropical cyclone's core has a negative effect on its development and intensity by diminishing atmospheric convection and introducing asymmetries in the storm's structure. Symmetric, strong outflow leads to a faster rate of intensification than observed in other systems by mitigating local wind shear. Weakening outflow is associated with the weakening of rainbands within a tropical cyclone. Tropical cyclones may still intensify, even rapidly, in

4712-401: A tropical cyclone's intensity or the direction it is traveling. Wind-pressure relationships (WPRs) are used as a way to determine the pressure of a storm based on its wind speed. Several different methods and equations have been proposed to calculate WPRs. Tropical cyclones agencies each use their own, fixed WPR, which can result in inaccuracies between agencies that are issuing estimates on

Hurricane Katrina - Misplaced Pages Continue

4864-568: A tropical wave, leaving cloudless skies, as convection is capped by the dry layer inversion. Additionally, any dust in the SAL reflects sunlight, cooling the air below it. Tropical waves in the Atlantic basin develop from low-pressure disturbances, which develop as far east as Sudan in east Africa , and drift across the continent into the Atlantic Ocean . These are generated or enhanced by

5016-418: A tropical wave. This normally occurs if upper-level wind shear is too strong. The storm can redevelop if the upper-level shear abates. If a tropical wave is moving quickly, or is organized enough, it can have winds of a strength in excess of tropical storm force, but it is not considered a tropical storm unless it has a closed low-level circulation. An example of this was Hurricane Claudette in 2003 , where

5168-480: A two-digit number and suffix letter by the warning centers that monitor them. Tropical wave West-moving waves can also form from the tail end of frontal zones in the subtropics and tropics, and may be referred to as easterly waves, but the waves are not properly called tropical waves. They are a form of inverted trough that shares many characteristics of a tropical wave. A tropical wave normally follows an area of sinking, intensely dry air, blowing from

5320-831: A typhoon. This happened in 2014 for Hurricane Genevieve , which became Typhoon Genevieve. Within the Southern Hemisphere, it is either called a hurricane, tropical cyclone or a severe tropical cyclone, depending on if it is located within the South Atlantic, South-West Indian Ocean, Australian region or the South Pacific Ocean. The descriptors for tropical cyclones with wind speeds below 65 kn (120 km/h; 75 mph) vary by tropical cyclone basin and may be further subdivided into categories such as "tropical storm", "cyclonic storm", "tropical depression", or "deep depression". The practice of using given names to identify tropical cyclones dates back to

5472-633: Is a strong tropical cyclone that occurs in the Atlantic Ocean or northeastern Pacific Ocean . A typhoon occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones". In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of 65  kn (120 km/h; 75 mph) or more. Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through

5624-499: Is almost impossible to determine the exact cause of some of the fatalities. A 2008 report by the Disaster Medicine and Public Health Preparedness journal indicates that 966 deaths can be directly attributed to the storm in Louisiana, including out of state evacuees, and another 20 indirectly (such as firearm-related deaths and gas poisoning). Due to uncertain causes of death with 454 evacuees, an upper-bound of 1,440

5776-415: Is assumed at this stage that a tropical cyclone has become self-sustaining and can continue to intensify without any help from its environment. Depending on its location and strength, a tropical cyclone is referred to by different names , including hurricane , typhoon , tropical storm , cyclonic storm , tropical depression , or simply cyclone . A hurricane is a strong tropical cyclone that occurs in

5928-406: Is calculated as: where p {\textstyle p} is the density of air, u {\textstyle u} is a sustained surface wind speed value, and d v {\textstyle d_{v}} is the volume element . Around the world, tropical cyclones are classified in different ways, based on the location ( tropical cyclone basins ), the structure of

6080-554: Is currently no consensus on how climate change will affect the overall frequency of tropical cyclones. A majority of climate models show a decreased frequency in future projections. For instance, a 2020 paper comparing nine high-resolution climate models found robust decreases in frequency in the Southern Indian Ocean and the Southern Hemisphere more generally, while finding mixed signals for Northern Hemisphere tropical cyclones. Observations have shown little change in

6232-414: Is cut off from its supply of warm moist maritime air and starts to draw in dry continental air. This, combined with the increased friction over land areas, leads to the weakening and dissipation of the tropical cyclone. Over a mountainous terrain, a system can quickly weaken. Over flat areas, it may endure for two to three days before circulation breaks down and dissipates. Over the years, there have been

Hurricane Katrina - Misplaced Pages Continue

6384-686: Is noted in the paper. A follow-up study by the Louisiana Department of Health & Hospitals determined that the storm was directly responsible for 1,170 fatalities in Louisiana. Federal disaster declarations covered 90,000 square miles (230,000 km) 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

6536-445: Is the generic term for a warm-cored, non-frontal synoptic-scale low-pressure system over tropical or subtropical waters around the world. The systems generally have a well-defined center which is surrounded by deep atmospheric convection and a closed wind circulation at the surface. A tropical cyclone is generally deemed to have formed once mean surface winds in excess of 35 kn (65 km/h; 40 mph) are observed. It

6688-512: Is the greatest. However, each particular basin has its own seasonal patterns. On a worldwide scale, May is the least active month, while September is the most active month. November is the only month in which all the tropical cyclone basins are in season. In the Northern Atlantic Ocean , a distinct cyclone season occurs from June 1 to November 30, sharply peaking from late August through September. The statistical peak of

6840-405: Is the storm's wind speed and r {\textstyle r} is the radius of hurricane-force winds. The Hurricane Severity Index is a scale that can assign up to 50 points to a system; up to 25 points come from intensity, while the other 25 come from the size of the storm's wind field. The IKE model measures the destructive capability of a tropical cyclone via winds, waves, and surge. It

6992-674: The African Easterly Jet . The clockwise circulation of the large transoceanic high-pressure cell or anticyclone centered near the Azores islands (known as the Azores High ) impels easterly waves away from the coastal areas of Africa towards North America . Tropical waves are the origin of approximately 60% of Atlantic tropical cyclones and of approximately 85% of intense Atlantic hurricanes ( Category 3 and greater). Tropical cyclones can sometimes degenerate back into

7144-620: The African easterly jet and areas of atmospheric instability give rise to cyclones in the Atlantic Ocean and Caribbean Sea . Heat energy from the ocean acts as the accelerator for tropical cyclones. This causes inland regions to suffer far less damage from cyclones than coastal regions, although the impacts of flooding are felt across the board. Coastal damage may be caused by strong winds and rain, high waves (due to winds), storm surges (due to wind and severe pressure changes), and

7296-513: The Atlantic Ocean or northeastern Pacific Ocean , and a typhoon occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones", and such storms in the Indian Ocean can also be called "severe cyclonic storms". Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their winds moving in

7448-647: The Hurricane Surge Index , the Hurricane Severity Index , the Power Dissipation Index (PDI), and integrated kinetic energy (IKE). ACE is a metric of the total energy a system has exerted over its lifespan. ACE is calculated by summing the squares of a cyclone's sustained wind speed, every six hours as long as the system is at or above tropical storm intensity and either tropical or subtropical. The calculation of

7600-539: The Lesser Antilles . On August 23, the 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

7752-503: 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 (26.6  inHg ). The pressure measurement made Katrina the fifth most intense Atlantic hurricane on record at

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7904-559: The Madden–Julian oscillation . The IPCC Sixth Assessment Report summarize the latest scientific findings about the impact of climate change on tropical cyclones. According to the report, we have now better understanding about the impact of climate change on tropical storm than before. Major tropical storms likely became more frequent in the last 40 years. We can say with high confidence that climate change increase rainfall during tropical cyclones. We can say with high confidence that

8056-700: The Miami metropolitan area , with a peak total of 16.43 in (417 mm) in Perrine . As a result, local flooding occurred in Miami-Dade County , damaging approximately 100 homes. Farther south in the Florida Keys, a tornado was spawned in Marathon on August 26. The tornado damaged a hangar at the airport there and caused an estimated $ 5 million in damage. The rains caused flooding, and

8208-460: The Saffir–Simpson scale . Climate oscillations such as El Niño–Southern Oscillation (ENSO) and the Madden–Julian oscillation modulate the timing and frequency of tropical cyclone development. Rossby waves can aid in the formation of a new tropical cyclone by disseminating the energy of an existing, mature storm. Kelvin waves can contribute to tropical cyclone formation by regulating

8360-575: The Saffir–Simpson scale . The trend was most clear in the North Atlantic and in the Southern Indian Ocean. In the North Pacific, tropical cyclones have been moving poleward into colder waters and there was no increase in intensity over this period. With 2 °C (3.6 °F) warming, a greater percentage (+13%) of tropical cyclones are expected to reach Category 4 and 5 strength. A 2019 study indicates that climate change has been driving

8512-539: The United States Coast Guard (USCG), National Hurricane Center (NHC), and National Weather Service (NWS), were commended for their actions, with the NHC being particularly praised for its accurate forecasts well in advance. Katrina was the earliest 11th named storm on record before being surpassed by Tropical Storm Kyle on August 14, 2020. The destruction and loss of life caused by the storm prompted

8664-549: The federally built levee system protecting metro New Orleans and the failure of the 40 Arpent Canal levee. Failures occurred in New Orleans and surrounding communities, especially St. Bernard Parish. The Mississippi River Gulf Outlet (MR-GO) breached its levees in approximately 20 places, flooding much of eastern New Orleans, most of St. Bernard Parish and the East Bank of Plaquemines Parish . The major levee breaches in

8816-495: The northeast . After the passage of the trough line, the wind veers southeast, the humidity abruptly rises, and the atmosphere destabilizes . This yields widespread showers and thunderstorms , sometimes severe . As the wave moves westward, the showers gradually diminish. An exception to the association of convection can occur in the Atlantic. Sometimes, a surge of dry air called the Saharan Air Layer (SAL) follows

8968-514: The troposphere , enough Coriolis force to develop a low-pressure center , and a pre-existing low-level focus or disturbance. There is a limit on tropical cyclone intensity which is strongly related to the water temperatures along its path. and upper-level divergence. An average of 86 tropical cyclones of tropical storm intensity form annually worldwide. Of those, 47 reach strength higher than 119 km/h (74 mph), and 20 become intense tropical cyclones, of at least Category 3 intensity on

9120-584: The Atlantic hurricane season is September 10. The Northeast Pacific Ocean has a broader period of activity, but in a similar time frame to the Atlantic. The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March and a peak in early September. In the North Indian basin, storms are most common from April to December, with peaks in May and November. In the Southern Hemisphere,

9272-656: The Bay St. Louis–Pass Christian bridge, and the Biloxi– Ocean Springs bridge. In addition, the eastbound span of the I-10 bridge over the Pascagoula River estuary was damaged. In the weeks after the storm, with the connectivity of the coastal U.S. Highway 90 shattered, traffic traveling parallel to the coast was reduced first to State Road 11 (parallel to I-10) then to two lanes on the remaining I-10 span when it

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9424-635: The Cochrane Bridge just outside Mobile. No significant damage resulted to the bridge and it was soon reopened. The damage on Dauphin Island was severe, with the surge destroying many houses and cutting a new canal through the western portion of the island. An offshore oil rig also became grounded on the island. As in Mississippi, the storm surge caused significant beach erosion along the Alabama coastline. More than 600,000 people lost power in Alabama as

9576-714: The Corps could not be held financially liable due to sovereign immunity in the Flood Control Act of 1928 . The 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 and New Orleans Police Department (NOPD) Superintendent Eddie Compass . Many other government officials faced criticism for their responses, especially New Orleans Mayor Ray Nagin , Louisiana Governor Kathleen Blanco , and President George W. Bush . However, several agencies, such as

9728-556: The Equator generally have their origins in the Intertropical Convergence Zone , where winds blow from either the northeast or southeast. Within this broad area of low-pressure, air is heated over the warm tropical ocean and rises in discrete parcels, which causes thundery showers to form. These showers dissipate quite quickly; however, they can group together into large clusters of thunderstorms. This creates

9880-574: 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. In Louisiana, the state's hurricane evacuation plan calls for local governments in areas along and near the coast to evacuate in three phases, starting with

10032-595: The Gulf Coast were covered under a voluntary or mandatory evacuation order. On the afternoon of August 26, the National Hurricane Center (NHC) realized that Katrina had yet to make the turn toward the Florida Panhandle and ended up revising the predicted track of the storm from the panhandle to the Mississippi coast. The National Weather Service's New Orleans/Baton Rouge office issued a vividly worded bulletin on August 28 predicting that

10184-405: 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

10336-826: The I-10 Twin Span Bridge traveling eastbound towards Slidell, Louisiana had collapsed. Both the Lake Pontchartrain Causeway and the Crescent City Connection only carried emergency traffic. However, access to downtown New Orleans and the "shelter of last resort" at the Convention Center was never closed because River Road in Jefferson Parish and Leake Avenue and Tchoupitoulas Street in New Orleans were not flooded, and would have allowed access throughout

10488-640: The Louisiana-Mississippi border was flooded from storm surge at the height of the storm. Other large Jackson County neighborhoods such as Porteaux Bay and Gulf Hills were severely damaged with large portions being completely destroyed, and St. Martin was hard hit; Ocean Springs, Moss Point , Gautier and Escatawpa also suffered major surge damage. Mississippi Emergency Management Agency officials also recorded deaths in Forrest , Hinds , Warren , and Leake counties. Over 900,000 people throughout

10640-798: 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,

10792-581: 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. Aircrews , many of whom lost their homes during the hurricane, began a round-the-clock rescue effort in New Orleans, and along the Mississippi and Alabama coastlines. President George W. Bush declared

10944-632: The PDI is similar in nature to ACE, with the major difference being that wind speeds are cubed rather than squared. The Hurricane Surge Index is a metric of the potential damage a storm may inflict via storm surge. It is calculated by squaring the dividend of the storm's wind speed and a climatological value (33 m/s or 74 mph), and then multiplying that quantity by the dividend of the radius of hurricane-force winds and its climatological value (96.6 km or 60.0 mi). This can be represented in equation form as: where v {\textstyle v}

11096-463: The South Atlantic is not a major basin, and not an official basin according to the WMO. Each year on average, around 80 to 90 named tropical cyclones form around the world, of which over half develop hurricane-force winds of 65 kn (120 km/h; 75 mph) or more. Worldwide, tropical cyclone activity peaks in late summer, when the difference between temperatures aloft and sea surface temperatures

11248-579: The Superdome, only six deaths were confirmed there, with four of these originating from natural causes , one from a drug overdose, and one a suicide. At the Convention Center, four bodies were recovered. One of the four is believed to be the result of a homicide. There is evidence that many prisoners were abandoned in their cells during the storm, while the guards sought shelter. Hundreds of prisoners were later registered as "unaccounted for". The Gulf coast of Mississippi suffered extremely severe damage from

11400-524: The U.S. Dept. of Housing and Urban Development, in St. Bernard Parish, 81% (20,229) of the housing units were damaged. In St. Tammany Parish, 70% (48,792) were damaged and in Plaquemines Parish 80% (7,212) were damaged. In addition, the combined effect of Hurricanes Katrina and Rita was the destruction of an estimated 562 square kilometres (217 sq mi) of coastal wetlands in Louisiana. As

11552-610: The United States National Hurricane Center and Fiji Meteorological Service issue alerts, watches and warnings for various island nations in their areas of responsibility. The United States Joint Typhoon Warning Center and Fleet Weather Center also publicly issue warnings about tropical cyclones on behalf of the United States Government . The Brazilian Navy Hydrographic Center names South Atlantic tropical cyclones , however

11704-610: The United States. The death toll from Katrina is uncertain, with reports differing by hundreds. According to the National Hurricane Center, 1,836 fatalities can be attributed to the storm: one in Kentucky , two each in Alabama, Georgia , and Ohio , 14 in Florida, 238 in Mississippi, and 1,577 in Louisiana. However, 135 people remain categorized as missing in Louisiana, and many of the deaths are indirect, but it

11856-591: The Western Pacific. Tropical cyclones have to have a significant amount of gale-force winds occurring around the center before they are named within the Southern Hemisphere . The names of significant tropical cyclones in the North Atlantic Ocean, Pacific Ocean, and Australian region are retired from the naming lists and replaced with another name. Tropical cyclones that develop around the world are assigned an identification code consisting of

12008-515: 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. Even in 2010, debris remained in some coastal communities. Before striking South Florida, Katrina traversed the Bahamas as a tropical storm. However, minimal impact was reported, with only "fresh breezes" on various islands. Although Hurricane Katrina stayed well to

12160-461: The airport on September 13 and regular carrier operations resumed in early October. Levee breaches in New Orleans also caused a significant number of deaths, with over 700 bodies recovered in New Orleans by October 23, 2005. Some survivors and evacuees reported seeing dead bodies lying in city streets and floating in still-flooded sections, especially in the east of the city. The advanced state of decomposition of many corpses, some of which were left in

12312-462: The area would be "uninhabitable for weeks" after "devastating damage" caused by Katrina, which at that time rivaled the intensity of Hurricane Camille . During video conferences involving the president later that day and on August 29, NHC director Max Mayfield expressed concern that Katrina might push its storm surge over the city's levees and flood walls. In one conference, he stated, "I do not think anyone can tell you with confidence right now whether

12464-540: The center and the storm's central pressure was 920 mbar (27 inHg). After moving over southeastern Louisiana and Breton Sound , it made its third and final landfall near the Louisiana–Mississippi border with 120 mph (190 km/h) sustained winds, still at a mid-range Category 3 hurricane intensity. Katrina maintained strength well into Mississippi, finally losing hurricane strength more than 150 miles (240 km) inland near Meridian, Mississippi . It

12616-526: The city included breaches at the 17th Street Canal levee, the London Avenue Canal , and the wide, navigable Industrial Canal , which left approximately 80% of the city flooded. Most of the major roads traveling into and out of the city were damaged. The only major intact highway routes out of the city were the westbound Crescent City Connection and the Huey P. Long Bridge, as large portions of

12768-482: The city. A June 2007 report by the American Society of Civil Engineers indicated that two-thirds of the flooding was caused by the multiple failures of the city's floodwalls. The storm surge also devastated the coasts of Mississippi and Alabama, making Katrina one of the most destructive hurricanes, the costliest natural disaster in the history of the United States (tied with Hurricane Harvey in 2017), and

12920-495: The coastal communities of Clermont Harbor and Waveland, much of Bay St. Louis, and flowed up the Jourdan River, flooding Diamondhead and Kiln . In Harrison County, Pass Christian was completely inundated, along with a narrow strip of land to the east along the coast, which includes the cities of Long Beach and Gulfport; the flooding was more extensive in communities such as D'Iberville, which borders Back Bay. Biloxi , on

13072-407: The coastal parishes of Orleans, Jefferson, and Plaquemines. The declaration actually did not include any of Louisiana's coastal parishes, whereas the coastal counties were included in the declarations for Mississippi and Alabama . Brown testified that this was because Louisiana Governor Blanco had not included those parishes in her initial request for aid, a decision that he found "shocking". After

13224-483: The combination of rains and winds downed trees and power lines, leaving 1.45 million people without power. Damage in South Florida was estimated at $ 523 million, mostly as a result of crop damage. Twelve deaths occurred in South Florida, of which three were caused by downed trees in Broward County, three from drowning in Miami-Dade County, three were from carbon monoxide poisoning caused by generators, one

13376-400: The computer models had shifted the potential path of Katrina 150 miles (240 km) westward from the Florida Panhandle, putting the city of New Orleans directly in 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. This scenario was considered a potential catastrophe because some parts of New Orleans and

13528-543: The deadliest hurricane since the 1928 Okeechobee hurricane . The total damage from Katrina is estimated at $ 125 billion (2005 U.S. dollars). However, in February 2021, a severe winter storm struck the United States, causing a major power failure in Houston, which caused at least $ 195 billion (2021 USD) in damage in Texas. It surpassed both Katrina and Harvey to become the single-costliest natural disaster recorded in

13680-435: The development of the westerlies . Cyclone formation is usually reduced 3 days prior to the wave's crest and increased during the 3 days after. The majority of tropical cyclones each year form in one of seven tropical cyclone basins, which are monitored by a variety of meteorological services and warning centers. Ten of these warning centers worldwide are designated as either a Regional Specialized Meteorological Centre or

13832-492: The equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies . When the subtropical ridge position shifts due to El Niño, so will the preferred tropical cyclone tracks. Areas west of Japan and Korea tend to experience much fewer September–November tropical cyclone impacts during El Niño and neutral years. During La Niña years, the formation of tropical cyclones, along with

13984-469: The evaporation of water from the ocean surface, which ultimately condenses into clouds and rain when moist air rises and cools to saturation . This energy source differs from that of mid-latitude cyclonic storms , such as nor'easters and European windstorms , which are powered primarily by horizontal temperature contrasts . Tropical cyclones are typically between 100 and 2,000 km (62 and 1,243 mi) in diameter. The strong rotating winds of

14136-444: The eye of Hurricane Katrina swept to the northeast, it subjected the city to hurricane conditions for hours. Although power failures prevented accurate measurement of wind speeds in New Orleans, there were a few measurements of hurricane-force winds; based on this information, the NHC concluded that much of the city likely experienced sustained winds of Category 1 or 2 hurricane strength. Katrina's storm surge caused 53 levee breaches in

14288-481: The eyewall of the storm, and an upper-level anticyclone helps channel this air away from the cyclone efficiently. However, some cyclones such as Hurricane Epsilon have rapidly intensified despite relatively unfavorable conditions. There are a number of ways a tropical cyclone can weaken, dissipate, or lose its tropical characteristics. These include making landfall, moving over cooler water, encountering dry air, or interacting with other weather systems; however, once

14440-410: The form of cold water from falling raindrops (this is because the atmosphere is cooler at higher altitudes). Cloud cover may also play a role in cooling the ocean, by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days. Conversely, the mixing of

14592-453: The frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the possible consequences of human-induced climate change. Tropical cyclones use warm, moist air as their fuel. As climate change is warming ocean temperatures , there is potentially more of this fuel available. Between 1979 and 2017, there was a global increase in the proportion of tropical cyclones of Category 3 and higher on

14744-532: The general public regarding forecasts, watches, and warnings. Since the systems can last a week or longer, and more than one can be occurring in the same basin at the same time, the names are thought to reduce the confusion about what storm is being described. Names are assigned in order from predetermined lists with one, three, or ten-minute sustained wind speeds of more than 65 km/h (40 mph) depending on which basin it originates. Standards vary from basin to basin. Some tropical depressions are named in

14896-485: The hearing, Blanco released a copy of her letter, which showed she had requested assistance for "all the southeastern parishes including the City of New Orleans" as well as specifically named 14 parishes, including Jefferson, Orleans, St. Bernard, and Plaquemines. Voluntary and mandatory evacuations were issued for large areas of southeast Louisiana as well as coastal Mississippi and Alabama. About 1.2 million residents of

15048-492: The hotel's glass exterior was completely sheared off. The Superdome , which was sheltering many people who had not evacuated, sustained significant damage. Two sections of the Superdome's roof were compromised and the dome's waterproof membrane was essentially peeled off. Louis Armstrong New Orleans International Airport was closed before the storm but did not flood. On August 30, it was reopened to humanitarian and rescue operations. Limited commercial passenger service resumed at

15200-963: 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. Many private caregiving facilities that relied on bus companies and ambulance services for evacuation were unable to evacuate their charges because they waited too long. 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, not enough bus drivers were available to drive them since Governor Blanco did not sign an emergency waiver to allow any licensed driver to transport evacuees on school buses. By August 26, many of

15352-482: The immediate post-storm emergency period. On August 29, at 7:40 am. CDT, it was reported that most of the windows on the north side of the Hyatt Regency New Orleans had been blown out, and many other high rise buildings had extensive window damage. The Hyatt was the most severely damaged hotel in the city, with beds reported to be flying out of the windows. Insulation tubes were exposed as

15504-439: The impact of Hurricane Katrina on August 29, leaving 238 people dead, 67 missing, and billions of dollars in damage: bridges, barges, boats, piers, houses, and cars were washed inland. Katrina traveled up the entire state; as a result, all 82 counties in Mississippi were declared disaster areas for federal assistance, 47 for full assistance. After making a brief initial landfall in Louisiana, Katrina had made its final landfall near

15656-451: The intensity from leveling off before an eye emerges in infrared imagery. The SATCON weights estimates from various satellite-based systems and microwave sounders , accounting for the strengths and flaws in each individual estimate, to produce a consensus estimate of a tropical cyclone's intensity which can be more reliable than the Dvorak technique at times. Multiple intensity metrics are used, including accumulated cyclone energy (ACE),

15808-522: The intensity of a tropical cyclone. Reconnaissance aircraft fly around and through tropical cyclones, outfitted with specialized instruments, to collect information that can be used to ascertain the winds and pressure of a system. Tropical cyclones possess winds of different speeds at different heights. Winds recorded at flight level can be converted to find the wind speeds at the surface. Surface observations, such as ship reports, land stations, mesonets , coastal stations, and buoys, can provide information on

15960-693: The late 1800s and early 1900s and gradually superseded the existing system—simply naming cyclones based on what they hit. The system currently used provides positive identification of severe weather systems in a brief form, that is readily understood and recognized by the public. The credit for the first usage of personal names for weather systems is generally given to the Queensland Government Meteorologist Clement Wragge who named systems between 1887 and 1907. This system of naming weather systems fell into disuse for several years after Wragge retired, until it

16112-465: The levees will be topped or not, but that's obviously a very, very great concern." 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

16264-404: The main belt of the Westerlies , by means of merging with a nearby frontal zone, can cause tropical cyclones to evolve into extratropical cyclones . This transition can take 1–3 days. Should a tropical cyclone make landfall or pass over an island, its circulation could start to break down, especially if it encounters mountainous terrain. When a system makes landfall on a large landmass, it

16416-462: The majority of the state. Katrina caused eleven tornadoes in Mississippi on August 29, some of which damaged trees and power lines. Battered by wind, rain and storm surge, some beachfront neighborhoods were completely leveled. Preliminary estimates by Mississippi officials calculated that 90% of the structures within half a mile of the coastline were completely destroyed, and that storm surges traveled as much as 6 miles (10 km) inland in portions of

16568-471: The metro area are below sea level. Since the storm surge produced by the hurricane's right-front quadrant (containing the strongest winds) was forecast to be 28 feet (8.5 m), while the levees offered protection to 23 feet (7.0 m), emergency management officials in New Orleans feared that the storm surge could go over the tops of levees protecting the city, causing major flooding. At a news conference at 10 am. EDT on August 28, shortly after Katrina

16720-515: The most on record in that state for one day in August. The most serious of these tornadoes was an F2 tornado which affected Heard County and Carroll County . This tornado caused three injuries and one fatality and damaged several houses. The other tornadoes caused significant damages to buildings and agricultural facilities. In addition to the fatality caused by the F2 tornado, there was another fatality in

16872-486: The mouth of the Pearl River , with the eye straddling St. Tammany Parish, Louisiana , and Hancock County, Mississippi , on the morning of August 29 at about 9:45 am. CDT. Hurricane Katrina also brought heavy rain to Louisiana, with 8–10 inches (200–250 mm) falling on a wide swath of the eastern part of the state. In the area around Slidell , the rainfall was even higher, and the highest rainfall recorded in

17024-540: The name Katrina to be retired by the World Meteorological Organization in April 2006. On January 4, 2023, the National Hurricane Center (NHC) updated the Katrina fatality data based on a report by Rappaport (2014) which reduced the number from an estimated 1,833 to 1,392. Hurricane Katrina originated from the merger of a tropical wave and the mid-level remnants of Tropical Depression Ten on August 19, 2005, near

17176-570: The north of Cuba , on August 28 it brought tropical-storm-force winds and rainfall of over 8 in (200 mm) to western regions of the island. Telephone and power lines were damaged and around 8,000 people were evacuated in the Pinar del Río Province . According to Cuban television reports the coastal town of Surgidero de Batabanó was 90% underwater. Hurricane Katrina first made landfall between Hallandale Beach and Aventura, Florida on August 25. The storm dropped heavy rainfall in portions of

17328-632: The northwestern portion of the state, though none of them caused significant damage. Throughout the Florida Panhandle, the storm resulted in an estimated $ 100 million in damage. There were two indirect fatalities from Katrina in Walton County as a result of a traffic accident. In the Florida Panhandle, 77,000 customers lost power. Overall, the hurricane killed 14 people and caused at least $ 623 million in damage. On August 29, 2005, Hurricane Katrina made landfall near Buras-Triumph, Louisiana , with 125 mph (200 km/h) winds, as

17480-522: The observed trend of rapid intensification of tropical cyclones in the Atlantic basin. Rapidly intensifying cyclones are hard to forecast and therefore pose additional risk to coastal communities. Warmer air can hold more water vapor: the theoretical maximum water vapor content is given by the Clausius–Clapeyron relation , which yields ≈7% increase in water vapor in the atmosphere per 1 °C (1.8 °F) warming. All models that were assessed in

17632-549: The original wave had winds of 45 mph (72 km/h) before developing a closed low-level circulation. It has been suggested that some eastern Pacific Ocean tropical cyclones are formed out of tropical easterly waves that originate in North Africa as well. After developing into a tropical cyclone, some of those systems can then reach the Central Pacific Ocean, such as Hurricane Lane in 2018. During

17784-466: The overall frequency of tropical cyclones worldwide, with increased frequency in the North Atlantic and central Pacific, and significant decreases in the southern Indian Ocean and western North Pacific. There has been a poleward expansion of the latitude at which the maximum intensity of tropical cyclones occurs, which may be associated with climate change. In the North Pacific, there may also have been an eastward expansion. Between 1949 and 2016, there

17936-440: The potential of spawning tornadoes . Climate change affects tropical cyclones in several ways. Scientists found that climate change can exacerbate the impact of tropical cyclones by increasing their duration, occurrence, and intensity due to the warming of ocean waters and intensification of the water cycle . Tropical cyclones draw in air from a large area and concentrate the water content of that air into precipitation over

18088-413: The presence of moderate or strong wind shear depending on the evolution and structure of the storm's convection. The size of tropical cyclones plays a role in how quickly they intensify. Smaller tropical cyclones are more prone to rapid intensification than larger ones. The Fujiwhara effect , which involves interaction between two tropical cyclones, can weaken and ultimately result in the dissipation of

18240-444: The release of latent heat from the saturated soil. Orographic lift can cause a significant increase in the intensity of the convection of a tropical cyclone when its eye moves over a mountain, breaking the capped boundary layer that had been restraining it. Jet streams can both enhance and inhibit tropical cyclone intensity by influencing the storm's outflow as well as vertical wind shear. On occasion, tropical cyclones may undergo

18392-492: The same intensity. The passage of a tropical cyclone over the ocean causes the upper layers of the ocean to cool substantially, a process known as upwelling , which can negatively influence subsequent cyclone development. This cooling is primarily caused by wind-driven mixing of cold water from deeper in the ocean with the warm surface waters. This effect results in a negative feedback process that can inhibit further development or lead to weakening. Additional cooling may come in

18544-492: The same system. The ASCAT is a scatterometer used by the MetOp satellites to map the wind field vectors of tropical cyclones. The SMAP uses an L-band radiometer channel to determine the wind speeds of tropical cyclones at the ocean surface, and has been shown to be reliable at higher intensities and under heavy rainfall conditions, unlike scatterometer-based and other radiometer-based instruments. The Dvorak technique plays

18696-513: The sea can result in heat being inserted in deeper waters, with potential effects on global climate . Vertical wind shear decreases tropical cyclone predicability, with storms exhibiting wide range of responses in the presence of shear. Wind shear often negatively affects tropical cyclone intensification by displacing moisture and heat from a system's center. Low levels of vertical wind shear are most optimal for strengthening, while stronger wind shear induces weakening. Dry air entraining into

18848-455: The state experienced power outages. Although Hurricane Katrina made landfall well to the west, Alabama and the Florida Panhandle were both affected by tropical-storm-force winds and a storm surge varying from 12 to 16 feet (3.7–4.9 m) around Mobile Bay , with higher waves on top. Sustained winds of 67 mph (108 km/h) were recorded in Mobile, Alabama , and the storm surge there

19000-478: 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

19152-445: The state line, and the eyewall passed over the cities of Bay St. Louis and Waveland as a Category 3 hurricane with sustained winds of 120 mph (190 km/h). Katrina's powerful right-front quadrant passed over the west and central Mississippi coast, causing a powerful 27-foot (8.2 m) storm surge, which penetrated 6 miles (10 km) inland in many areas and up to 12 miles (19 km) inland along bays and rivers; in some areas,

19304-475: The state was approximately 15 inches (380 mm). As a result of the rainfall and storm surge the level of Lake Pontchartrain rose and caused significant flooding along its northeastern shore, affecting communities from Slidell to Mandeville . Several bridges were destroyed, including the I-10 Twin Span Bridge connecting Slidell to New Orleans. Almost 900,000 people in Louisiana lost power as

19456-513: The state's coast. One apartment complex with approximately thirty residents seeking shelter inside collapsed. More than half of the 13 casinos in the state, which were floated on barges to comply with Mississippi land-based gambling laws, were washed hundreds of yards inland by waves. A number of streets and bridges were washed away. On U.S. Highway 90 along the Mississippi Gulf Coast, two major bridges were completely destroyed:

19608-481: The storm came ashore. Some estimates claimed that 80% of the 1.3 million residents of the greater New Orleans metropolitan area evacuated, leaving behind substantially fewer people than remained in the city during the Hurricane Ivan evacuation. On August 29, 2005, Katrina's storm surge caused 53 breaches to various flood protection structures in and around the greater New Orleans area, submerging 80% of

19760-617: The subtropical ridge position, shifts westward across the western Pacific Ocean, which increases the landfall threat to China and much greater intensity in the Philippines . The Atlantic Ocean experiences depressed activity due to increased vertical wind shear across the region during El Niño years. Tropical cyclones are further influenced by the Atlantic Meridional Mode , the Quasi-biennial oscillation and

19912-419: The summer months, tropical waves can extend northward as far as the desert of the southwestern United States, producing spells of intensified shower activity embedded within the prevailing monsoon regime. A screaming eagle is a tropical wave with a convective pattern that loosely resembles the head of an eagle. This phenomenon is caused by shearing from either westerly winds aloft or strong easterly winds at

20064-419: The surface pressure decreases by 2.5 hPa (0.074 inHg) per hour for at least 12 hours or 5 hPa (0.15 inHg) per hour for at least 6 hours. For rapid intensification to occur, several conditions must be in place. Water temperatures must be extremely high, near or above 30 °C (86 °F), and water of this temperature must be sufficiently deep such that waves do not upwell cooler waters to

20216-483: The surface. On the other hand, Tropical Cyclone Heat Potential is one of such non-conventional subsurface oceanographic parameters influencing the cyclone intensity. Wind shear must be low. When wind shear is high, the convection and circulation in the cyclone will be disrupted. Usually, an anticyclone in the upper layers of the troposphere above the storm must be present as well—for extremely low surface pressures to develop, air must be rising very rapidly in

20368-408: The surface. These systems are typically located within 25 degrees latitude of the equator. Rain showers and surface winds gusting to 29 mph (47 km/h) are associated with these waves. They move across the ocean at a rate of 15 mph (24 km/h). Strong thunderstorm activity can be associated with the features when located east of a tropical upper tropospheric trough . The term

20520-612: The surge crossed Interstate 10 for several miles. Hurricane Katrina brought strong winds to Mississippi, which caused significant tree damage throughout the state. The highest unofficial reported wind gust recorded from Katrina was one of 135 mph (217 km/h) in Poplarville , in Pearl River County . The storm also brought heavy rains with 8–10 inches (200–250 mm) falling in southwestern Mississippi and rain in excess of 4 inches (100 mm) falling throughout

20672-648: The system and its intensity. For example, within the Northern Atlantic and Eastern Pacific basins, a tropical cyclone with wind speeds of over 65  kn (120 km/h; 75 mph) is called a hurricane , while it is called a typhoon or a severe cyclonic storm within the Western Pacific or North Indian oceans. When a hurricane passes west across the International Dateline in the Northern Hemisphere, it becomes known as

20824-552: The third major hurricane of the 2005 Atlantic hurricane season . It was also the fourth-most intense Atlantic hurricane to make landfall in the contiguous United States , gauged by barometric pressure. Katrina formed on August 23, 2005, with the merger of a tropical wave and the remnants of Tropical Depression Ten . Early the following day, the depression intensified into a tropical storm and headed generally westward toward Florida. On August 25, two hours before making landfall at Hallandale Beach , it strengthened into

20976-545: 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

21128-423: The tropical cyclone year begins on July 1 and runs all year-round encompassing the tropical cyclone seasons, which run from November 1 until the end of April, with peaks in mid-February to early March. Of various modes of variability in the climate system, El Niño–Southern Oscillation has the largest effect on tropical cyclone activity. Most tropical cyclones form on the side of the subtropical ridge closer to

21280-685: The water or sun for days before being collected, hindered efforts by coroners to identify many of the dead. The first deaths reported from the city were reported shortly before midnight on August 28, as three nursing home patients died during an evacuation to Baton Rouge , most likely from dehydration. An estimated 215 bodies were found in nursing homes and hospitals in New Orleans, the largest number being at Memorial Medical Center where 45 corpses were recovered. Some 200 patients at Charity Hospital were not evacuated until Friday, September 2, having been without power or fresh water for five days. While there were also early reports of fatalities amid mayhem at

21432-451: The weaker of two tropical cyclones by reducing the organization of the system's convection and imparting horizontal wind shear. Tropical cyclones typically weaken while situated over a landmass because conditions are often unfavorable as a result of the lack of oceanic forcing. The Brown ocean effect can allow a tropical cyclone to maintain or increase its intensity following landfall , in cases where there has been copious rainfall, through

21584-402: The wind speed of Hurricane Helene by 11%, it increased the destruction from it by more than twice. According to World Weather Attribution the influence of climate change on the rainfall of some latest hurricanes can be described as follows: Tropical cyclone intensity is based on wind speeds and pressure. Relationships between winds and pressure are often used in determining the intensity of

21736-795: Was 185 kn (95 m/s; 345 km/h; 215 mph) in Hurricane Patricia in 2015—the most intense cyclone ever recorded in the Western Hemisphere . Warm sea surface temperatures are required for tropical cyclones to form and strengthen. The commonly-accepted minimum temperature range for this to occur is 26–27 °C (79–81 °F), however, multiple studies have proposed a lower minimum of 25.5 °C (77.9 °F). Higher sea surface temperatures result in faster intensification rates and sometimes even rapid intensification . High ocean heat content , also known as Tropical Cyclone Heat Potential , allows storms to achieve

21888-527: Was a slowdown in tropical cyclone translation speeds. It is unclear still to what extent this can be attributed to climate change: climate models do not all show this feature. A 2021 study review article concluded that the geographic range of tropical cyclones will probably expand poleward in response to climate warming of the Hadley circulation . When hurricane winds speed rise by 5%, its destructive power rise by about 50%. Therfore, as climate change increased

22040-540: Was approximately 12 feet (3.7 m). The surge caused significant flooding several miles inland along Mobile Bay. Four tornadoes were also reported in Alabama. Ships, oil rigs, boats and fishing piers were washed ashore along Mobile Bay: the cargo ship M/V Caribbean Clipper and many fishing boats were grounded at Bayou La Batre . An oil rig under construction along the Mobile River broke its moorings and floated 1.5 miles (2.4 km) northwards before striking

22192-471: Was designed and built by the Orleans Levee Board . The search for the missing was undertaken by the St. Bernard Fire Department because of the assets of the United States Coast Guard being diverted to New Orleans. In the months after the storm, many of the missing were tracked down by searching flooded homes, tracking credit card records, and visiting homes of family and relatives. According to

22344-453: 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. 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

22496-544: Was due to a vehicle accident, one occurred during debris cleanup, and one was associated with a lack of electricity. Significant impacts were also reported in the Florida Panhandle . Although Katrina moved ashore in Louisiana and Mississippi, its outer periphery produced a 5.37 ft (1.64 m) storm surge in Pensacola . High waves caused beach erosion and closed nearby roadways. There were five tornadoes in

22648-508: Was due to flooding caused by engineering flaws in the flood protection system, particularly the levees around the city of New Orleans. 80% of the city, as well as large areas in neighboring parishes , were flooded for weeks. The flooding destroyed most of New Orleans's transportation and communication facilities, leaving tens of thousands of people who did or could not evacuate the city before landfall with little access to food, shelter, and other necessities. The disaster in New Orleans prompted

22800-432: Was opened. All three coastal counties of the state were severely affected by the storm. Katrina's surge was the most extensive, as well as the highest, in the documented history of the United States; large portions of Hancock , Harrison , and Jackson counties were inundated by the storm surge, in all three cases affecting most of the populated areas. Surge covered almost the entire lower half of Hancock County, destroying

22952-585: Was revived in the latter part of World War II for the Western Pacific. Formal naming schemes have subsequently been introduced for the North and South Atlantic, Eastern, Central, Western and Southern Pacific basins as well as the Australian region and Indian Ocean. At present, tropical cyclones are officially named by one of twelve meteorological services and retain their names throughout their lifetimes to provide ease of communication between forecasters and

23104-444: Was upgraded to a Category 5 storm, New Orleans mayor Ray Nagin ordered the first-ever mandatory evacuation of the city, calling Katrina "a storm that most of us have long feared". The city government also established several "refuges of last resort" for citizens who could not leave the city, including the massive Louisiana Superdome , which sheltered approximately 26,000 people and provided them with food and water for several days as

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