Hurricane Harvey

This article is about the Atlantic hurricane of 2017. For other storms of the same name, see Tropical Storm Harvey.

Hurricane Harvey

Category 4 major hurricane (SSHWS/NWS)
Hurricane Harvey near peak intensity prior to landfall in southern Texas on August 25
Formed	August 17, 2017 (2017-08-17)
Dissipated	Currently active
(Extratropical after September 1)
Highest winds	1-minute sustained: 130 mph (215 km/h)
Lowest pressure	938 mbar (hPa); 27.7 inHg
Fatalities	48 confirmed (as of September 1)
Damage	Unknown (Estimated in tens of billions)
Areas affected	Windward Islands, Suriname, Guyana, Nicaragua, Honduras, Belize, Yucatán Peninsula, United States (particularly Texas)
Part of the 2017 Atlantic hurricane season

Hurricane Harvey was the first major hurricane to make landfall in the United States since Wilma in 2005, ending a record 12-year period with no hurricanes of Category 3 intensity or higher making landfall in the United States. In a four-day period, many areas received more than 40 inches (1,000 mm) of rain as the system meandered over eastern Texas and adjacent waters, causing catastrophic flooding. With peak accumulations of 51.88 in (1,318 mm), Harvey is the wettest tropical cyclone on record in the contiguous United States. The resulting floods inundated hundreds of thousands of homes, displaced more than 30,000 people, and prompted more than 13,000 rescues.

The eighth named storm, third hurricane, and the first major hurricane of the 2017 Atlantic hurricane season, Harvey developed from a tropical wave to the east of the Lesser Antilles, reaching tropical storm status on August 17. The storm crossed through the Windward Islands on the following day, passing just south of Barbados and later near Saint Vincent. Upon entering the Caribbean Sea, Harvey began to weaken due to moderate wind shear and degenerated into a tropical wave north of Colombia early on August 19. The remnants were monitored for regeneration as it continued west-northwestward across the Caribbean and the Yucatán Peninsula, before redeveloping over the Bay of Campeche on August 23. Harvey then began to rapidly intensify on August 24, regaining tropical storm status and becoming a hurricane later that day. While the storm moved generally northwest, Harvey's intensification phase stalled slightly overnight from August 24–25, however Harvey soon resumed strengthening and became a Category 4 hurricane late on August 25. Hours later, Harvey made landfall near Rockport, Texas, at peak intensity.

Harvey has caused at least 48 confirmed deaths; 1 in Guyana, and 47 in the United States. Catastrophic inland flooding is ongoing in the Greater Houston metropolitan area. FEMA director Brock Long called Harvey the worst disaster in Texas history, and expected the recovery to take many years. Preliminary estimates of economic losses range from $10 billion to $160 billion, with a large portion of losses sustained by uninsured homeowners.

Meteorological history

Map plotting the track and intensity of the storm according to the Saffir–Simpson hurricane wind scale

Early on August 13, the National Hurricane Center (NHC) began monitoring a tropical wave on the western coast of Africa. Amid favorable environmental conditions, the wave was expected to merge with a broad area of low pressure southwest of Cape Verde and gradually organize thereafter. Instead, the two disturbances remained separate, with the broad trough continuing westward and the tropical wave moving farther north. On August 17, shower and thunderstorm activity in association with the trough began to show signs of organization, while high-resolution satellite showed an increasingly defined low-level circulation. As such, the NHC initiated advisories on a potential tropical cyclone, allowing tropical storm watches and warnings to be hoisted for portions of the Lesser Antilles. An Air Force Reserve Hurricane Hunter aircraft deployed to the disturbance later that afternoon found a well-defined center and tropical storm-force winds, prompting the NHC to upgrade it to Tropical Storm Harvey at 21:00 UTC.

View from a NOAA Hurricane Hunter aircraft flying through the eye of the storm on August 24

Following its designation, the cyclone moved swiftly westward into the Caribbean Sea under the influence of an expansive ridge of high pressure to its north. An environment of moderate wind shear complicated the forecast of the storm's intensity, with global forecast models suggesting dissipation in the central Caribbean, whereas statistical and hurricane models suggested the potential for Harvey to be near hurricane strength in later days. Over the next day, the storm changed little in structure, remaining poorly organized with its low-level center on the eastern edge of associated deep convection. Harvey's presentation began to deteriorate early on August 19; its convective pattern became elongated while the circulation became less defined. In fact, a reconnaissance aircraft was unable to find a loosely-closed circulation at 850 mb (4,781 ft), though it did locate one at lower levels. Harvey was downgraded to a tropical depression at 21:00 UTC on August 19; six hours later, based on continued data from a reconnaissance aircraft, it was declared an open tropical wave. Early on August 20, the NHC began monitoring the remnants of Harvey for redevelopment. Although the effects of strong upper-level winds and dry air were expected to limit development in the near-term, conditions were expected to become more conducive to tropical storm and hurricane conditions when the disturbance entered the northwestern Caribbean Sea, and especially in the Bay of Campeche. Despite an increase in convective organization, the disturbance still lacked a well-defined center as it approached the Yucatán Peninsula. While traversing inland, satellite images and surface observations indicated that the circulation became better defined. A reconnaissance aircraft investigating the remnants of Harvey around 15:00 UTC on August 23 indicated that it once again acquired a well-defined center, and the NHC upgraded it to a tropical depression accordingly. The system began to slowly consolidate amid an increasingly favorable environment, attaining tropical storm intensity by 06:00 UTC on August 24.

Harvey as a hurricane on August 24

Later that morning, Harvey began to undergo rapid intensification as an eye developed and its central pressure quickly fell. By 17:00 UTC, the storm was upgraded to the third hurricane of the season. Slight entrainment of dry air slowed the intensification process, however, by the next day, Harvey was able to quickly strengthen into a major hurricane by 19:00 UTC. Further deepening occurred as the storm approached the coast of Texas, with Harvey becoming a Category 4 hurricane at 23:00 UTC, based on reconnaissance aircraft data. Around 03:00 UTC on August 26, the hurricane made landfall at peak intensity at Rockport with winds of 130 mph (215 km/h) and an atmospheric pressure of 938 mbar (27.7 inHg). Harvey became the first major hurricane to make landfall in the United States since Wilma in 2005 and the strongest in terms of wind speed to hit the country since Charley in 2004. It was the first hurricane to strike Texas since Ike in 2008, the first major hurricane in the state since Bret in 1999, and the strongest in Texas since Carla in 1961.

After striking land, the storm moved over the Copano Bay and made a second landfall in Texas just north of Holiday Beach at 06:00 UTC on August 26 as a Category 3 hurricane.Afterwards, rapid weakening ensued as its speed slowed dramatically to a crawl, and weakened to a tropical storm at 18:00 UTC on August 26.

Preparations

Caribbean and Latin America

Tropical Storm Harvey in the Eastern Caribbean on August 18

Tropical cyclone warnings and watches for the Windward Islands were issued starting at 15:00 UTC on August 17, about six hours before Harvey developed. At that time, a tropical storm watch was posted for Dominica, while a tropical storm warning became in effect in Barbados, Martinique, Saint Lucia, and Saint Vincent and the Grenadines. All watches and warnings were discontinued by late on August 18, as the storm continued westward into the Caribbean.

In Honduras, a green alert was issued for the Atlántida, Islas de la Bahía, Colón, Cortés, Gracias a Dios, Olancho, and Yoro departments. About 8 inches (20 cm) of precipitation was expected along the coast, while inland areas were forecast to receive 2.76 to 3.15 in (7.0 to 8.0 cm) of rain. As the remnants of Harvey approached Mexico, the Civil Protection Secretary of the state of Campeche issued a blue alert, indicting minimal danger. When Harvey redeveloped at 15:00 UTC on August 23, the Government of Mexico issued a tropical storm watch in Tamaulipas from Boca De Catan to the mouth of the Rio Grande. The watch remained in effect until 21:00 UTC on August 25, after it became evident that the storm no longer posed a significant threat to that area.

United States

FEMA worked with the Coast Guard, Customs and Border Protection, and Immigration and Customs Enforcement to prepare for the storm and its aftermath. The agency placed disaster response teams on standby at emergency posts in Austin, Texas, and Baton Rouge, Louisiana.

Video briefings by officials

• Play media

  Comments from the White House (begin at 25:50)

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  Comments from National Weather Service director Louis Uccellini

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  Shelter in place briefing by FEMA

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  Comments on evacuations in Galveston, Texas, by Mayor James Yarbrough

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  Comments by the Governor of Texas

Texas

Members of the Texas National Guard, local police, and firefighters coordinating relief efforts

Upon the NHC resuming advisories for Harvey at 15:00 UTC on August 23, a hurricane watch was issued in Texas from Port Mansfield to San Luis Pass, while a tropical storm watch was posted from Port Mansfield south to the mouth of the Rio Grande and from San Luis Pass to High Island. Additionally, a storm surge watch became in effect from Port Mansfield to High Island. Additional watches and warnings were posted in these areas at 09:00 UTC on August 24, with a hurricane warning from Port Mansfield to Matagorda; a tropical storm warning from Matagorda to High Island; a hurricane watch and tropical storm warning from Port Mansfield to the Rio Grande; a storm surge warning from Port Mansfield to San Luis Pass; and a storm surge from Port Mansfield to the Rio Grande. The watches and warnings were adjusted accordingly after Harvey moved inland and began weakening, with the warning discontinued at 15:00 UTC on August 26. By 09:00 UTC on the following day, only a tropical storm warning and a storm surge warning remained in effect from Port O'Connor to Sargent. However, watches and warnings were re-issued as Harvey began to re-emerge into the Gulf of Mexico, and beginning at 15:00 UTC on August 28, a tropical storm warning was in effect for the entire Gulf Coast of Texas from High Island northward.

Governor Greg Abbott declared a state of emergency for 30 counties on August 23, while mandatory evacuations were issued for Brazoria, Calhoun, Jackson, Refugio, San Patricio, and Victoria counties, as well as parts of Matagorda County. On August 26, Governor Abbott added an additional 20 counties to the state of emergency declaration. Furthermore, the International Charter on Space and Major Disasters was activated by the USGS on behalf of the Governor's Texas Emergency Management Council, including the Texas Division of Emergency Management, thus providing for humanitarian satellite coverage.

Louisiana

In Louisiana, Governor John Bel Edwards declared a state of emergency for the entire state. A mandatory evacuation was ordered in Cameron Parish for the cities of Big Lake, Cameron, Creole, Grand Chenier, Hackberry, Holly Beach, and Johnson Bayou. Additionally, a voluntary evacuation was ordered in Vermilion Parish for low-lying areas south of State Highway 14. The Louisiana National Guard prepared about 500,000 sandbags and emergency boats and high-water-rescue vehicles were placed on standby should flooding occur. In New Orleans, there were concerns about whether or not the city's drainage system could handle a heavy rainfall event, with only 105 of the 120 water pumps being operational and some power turbines being out of service. The city's public schools, as well as six universities and a medical school, closed on August 29. As Harvey began re-emerging into the Gulf of Mexico on August 28, the tropical storm warning in Texas from Mesquite Bay to High Island was extended eastward into Louisiana to the community of Cameron at 12:00 UTC, while a tropical storm watch was issued from Cameron to Intracoastal City.

Effects in the Caribbean and Latin America

Winds left residents throughout Barbados without electricity, with a majority of outages occurring in Christ Church, Saint Joseph, Saint Lucy, and Saint Michael provinces. Flooding washed one house off its foundation, while water entered some houses, forcing some people to evacuate. Bridges in Saint Andrew and Saint Joseph were damaged. Additionally, a fuel depot in Speightstown was flooded. Winds deroofed a church. In Saint Vincent and the Grenadines, nine homes were flooded and four others experienced wind damage. Additionally, a tree fell on a school, damaging the building. Blocked drains in Port Elizabeth resulted in more than 15 businesses being flooded. A total of 15 people were housed in shelters after the storm.

Strong winds and heavy rainfall also affected Suriname and Guyana. In the former, high winds in the capital city of Paramaribo caused roof damage to the Presidential Palace and two homes, while the Torarica Hotel and Casino suffered structural impact. Additionally, four dwellings were deroofed in Commewijne and three others lost their roofs in Wanica; in the latter, the Ministry of Social Affairs building was damaged by falling trees. In Guyana, the village of Jawalla bore the brunt of the storm. Four homes were demolished, while five other residences and two shops were damaged. Several public buildings were also damaged, including the community center, the village council buildings, the nursery, and public schools. A 29-year-old woman died after her house collapsed on her.

Effects in the United States

Video report from Voice of America on August 30, 2017

Texas

Throughout Texas, more than 300,000 people were left without electricity and billions of dollars of property damage was sustained. At least 46 people were killed, though that number was expected to rise. By August 29, approximately 13,000 people had been rescued across the state while an estimated 30,000 were displaced. The refinery industry capacity was reduced, and oil and gas production was affected in the Gulf of Mexico and inland Texas. On Monday, various news outlets announced the closure of oil refineries ahead of Hurricane Harvey, creating an artificial fuel shortage; a “run to the pump” ensued. Panicked, motorists waited in long lines. Consequently, gas stations through the state were forced to close due to the rush. More than 48,700 homes were affected by Harvey throughout the state, including over 1,000 that were completely destroyed and more than 17,000 that sustained major damage; approximately 32,000 sustained minor damage. Nearly 700 businesses were damaged as well.

Landfall area

Coast Guard video during an overflight from Port Aransas to Port O'Connor, Texas, Aug. 26, 2017

Making landfall as a Category 4, Harvey inflicted tremendous damage across Aransas County. Wind gusts were observed up to 132 mph (212 km/h) near Port Aransas. In Rockport, entire blocks were leveled by the hurricane's winds. The city's courthouse was severely damaged when a cargo trailer was hurled into it, coming to a stop halfway through the structure. The gymnasium of the Rockport-Fulton High School lost multiple walls while the school itself suffered some damage. A Fairfield Inn in the city was severely damaged. One person died in a house fire in the city, unable to be rescued due to the extreme weather conditions. As of August 28, an estimated 30–40 people remain unaccounted for across Aransas County, including 9 in Rockport. Nearly every structure in Port Aransas suffered damage. By the afternoon of August 26, more than 20 in (51 cm) of rain had fallen in the Corpus Christi metropolitan area. All of Victoria was left without water and most had no power.

Houston metropolitan area flooding

Rainfall accumulation from August 23 through August 29. Animation by NASA

Drone photography of flooding in Houston

Many locations in the Houston metropolitan area observed at least 30 in (76 cm) of precipitation, with a maximum of 51.88 in (131.8 cm) in Cedar Bayou. This makes Harvey the wettest tropical cyclone on record for Texas, and the contiguous United States, surpassing the previous rainfall record held by Tropical Storm Amelia. The local National Weather Service office in Houston observed all-time record daily rainfall accumulations on both August 26 and 27, measured at 14.4 in (37 cm) and 16.08 in (40.8 cm) respectively. The 39.11 in (790 mm) of rain in August made the month the wettest ever recorded in Houston since record keeping began in 1892, more than doubling the previous record of 19.21 in (488 mm) in June 2001.

During the storm, more than 800 Houston area flights were canceled, including 704 at George Bush Intercontinental Airport and 123 at William P. Hobby Airport. Both airports eventually closed. Several tornadoes were spawned in the area, one of which damaged or destroyed the roofs of dozens of homes in Sienna Plantation. As of August 29, 14 fatalities have been confirmed from flooding in the Houston area, including 6 from the same family who died when their van was swept off a flooded bridge. A police officer drowned while trying to escape rising waters.

Soldiers with the Texas Army National Guard move through flooded Houston streets as floodwaters from Hurricane Harvey continue to rise.

An estimated 25–30 percent of Harris County—roughly 444 mi² (1,150 km²) of land—was submerged.

U.S. Navy Sailors conduct a search and rescue mission above a residence in Beaumont, Texas

Late on August 27, a mandatory evacuation was issued for all of Bay City as model projections indicated the downtown area would be inundated by 10 ft (3.0 m) of water. Flooding was anticipated to cut off access to the city around 1:00 p.m. CDT on August 28. Evacuations took place in Conroe on August 28 following release of water from the Lake Conroe dam. On the morning on August 29, a levee collapsed along Columbia Lakes in Brazoria County, prompting officials to urgently request everyone in the area evacuate.

On August 28, the U.S. Army Corps of Engineers began controlled water releases from Addicks and Barker Reservoirs in the Buffalo Bayou watershed in an attempt to manage flood levels in the immediate area. According to the local Corps commander, "It’s going to be better to release the water through the gates directly into Buffalo Bayou as opposed to letting it go around the end and through additional neighborhoods and ultimately into the bayou." At the time the releases started, the reservoirs had been rising at more than 6 inches (15 cm) per hour. Many people began evacuating the area, fearing a levee breach. Despite attempts to alleviate the water rise, the Addicks Reservoir reached capacity on the morning of August 29 and began spilling out. The NASA Johnson Space Center has been closed to employees and visitors due to the flooding until September 5. Only the critical mission control staff remain and reside in the control rooms to monitor procedures of the International Space Station.

Deep East Texas and Beaumont–Port Arthur area

“ Anyone who chooses to not [evacuate] cannot expect to be rescued and should write their social security numbers in permanent marker on their arm so their bodies can be identified. The loss of life and property is certain. GET OUT OR DIE! ” — Jacques Blanchette, Tyler County Emergency Management

The Beaumont–Port Arthur metropolitan area also experienced torrential precipitation, including 32.55 in (82.7 cm) of rainfall in Beaumont. Rising waters of the Neches River caused the city to lose service from its main pump station, as well as its secondary water source in Hardin County, cutting water supply to the city for an unknown amount of time. Flooding to the north and east of the Houston area resulted in mandatory evacuations for portions of Liberty, Jefferson, and Tyler counties, while Jasper and Newton counties were under a voluntary evacuation. One death occurred in Beaumont when a woman exited her disabled vehicle, but was swept away. In Port Arthur, the mayor stated that the entire city was submerged by water. Hundreds of displaced residents went to the Robert A. "Bob" Bowers Civic Center for shelter, but they were evacuated again after the building began to flood. Water entered at least several hundreds of homes in Jefferson County.

Louisiana

Heavy rainfall extended eastward into Louisiana, with the state recording up to 14.88 in (37.8 cm) of precipitation near the town of Iowa. In Lake Charles, water reached 4 ft (1.2 m) in height, with homes flooded and hundreds of people forced to evacuate in one neighborhood alone. Throughout the state, about 500 people were rescued by August 28, while 269 people went to a shelter in southwest Louisiana, about 200 of whom were rescued from their homes. An EF2 tornado near Evangeline damaged four homes, one of which was destroyed. The tornado also damaged fences, a motorcycle, a pickup truck, and toppled three electrical poles.

Elsewhere

In Alabama, a tornado in the vicinity of Reform damaged two homes and destroyed a barn along State Route 17, while four people were hospitalized for their injuries. A possible tornado in Lamar County near Kennedy caused damage to trees and roofs. In Tennessee, more than 19,000 people lost electricity in Memphis. Low-lying streets in the area were inundated with water. One indirect death occurred in Memphis due to a weather-related head-on collision of a car and a tractor trailer on Interstate 40. Heavy rainfall in Nashville inundated a number of roads and flooded an apartment complex, resulting in the evacuation of 13 people. Overall, about 50 people in the city evacuated from flooded areas.

Energy production

Main article: 2017 Arkema plant explosion

Energy production in the Gulf of Mexico declined in the wake of Harvey by approximately 21% — 378,633 barrels per day of the 1.75 million barrels of oil produced each day. Natural gas production declined by about 25.71% — 827.89 million metric standard cubic meters per day (MMSCFD). The Eagle Ford Rock Formation (shale oil and gas) in southern Texas reduced production by 300,000 to 500,000 bpd, according to the Texas Railroad Commission. Many energy-related ports and terminals are closed, delaying about fourteen crude oil tankers. About 2.25 million bpd of refining capacity was offline for several days; that is about 12% of total US capacity, with refineries affected at Corpus Christi, and later Port Arthur and Beaumont, and Lake Charles, Louisiana. The price of Brent crude versus West Texas Intermediate crude oil achieved a split of U.S. $5.

Two ExxonMobil refineries had to be shut down following related storm damage and releases of hazardous pollutants. Two oil storage tanks owned by Burlington Resources Oil and Gas collectively spilled 30,000 gallons of crude in DeWitt County. An additional 8,500 gallons of wastewater was spilled in the incidents.

On August 30, the CEO of Arkema warned one of its chemical plants in Crosby, Texas, could explode or be subject to intense fire due to the loss of "critical refrigeration" of materials. All workers at the facility and residents within 1.5 mi (2.4 km) were evacuated. Eight of the plant's nine refrigeration units failed without power, enabling the stored chemicals to decompose and become combustible. Two explosions occurred around 2:00 a.m. on August 31; 21 emergency personnel were briefly hospitalized.

Athletics

The flooding in Houston from the storm required the traditional Governor's Cup National Football League preseason game between the Dallas Cowboys and the Houston Texans scheduled for August 31 to be moved from NRG Stadium in Houston to AT&T Stadium in Arlington, Texas. The game was later cancelled to allow the Houston Texans players to return to Houston after the storm. In addition, the Houston Astros were forced to move their August 29–31 series with the Texas Rangers from Minute Maid Park in Houston to Tropicana Field in St. Petersburg, Florida. The annual Texas Kickoff game that was to feature BYU and LSU to kick off the 2017 college football season was moved to the Mercedes-Benz Superdome in New Orleans, Louisiana. The NCAA FBS football game between Houston and UTSA was postponed due to the aftermath of the storm. It was originally scheduled for September 2 at the Alamodome in San Antonio and is expected to be rescheduled.

The Houston Dynamo rescheduled a planned Major League Soccer match against Sporting Kansas City on August 26 to October 11. The Houston Dash of the National Women's Soccer League rescheduled their August 27 match against the North Carolina Courage to a date that has not been announced. Both teams moved their training camps to Toyota Stadium in Frisco, Texas (near Dallas) while preparing for their next matches; the Dash's match the following week, against the Seattle Reign, will be played in Frisco, with all proceeds from ticket sales benefiting an American Red Cross relief fund for hurricane victims. The Dynamo and Major League Soccer also donated a combined $1 million into the hurricane relief fund, while also opening BBVA Compass Stadium to accept donated supplies for processing and distribution.

Athletic events were rescheduled as far away as Kentucky, where the storm's remnants were expected to cause heavy rains on September 1, interfering with Friday night high school football across the state. More than 50 high schools in the state moved games that had been scheduled for Friday to either Thursday or Saturday.

Aftermath

'President Trump Participates in a Tour of the Emergency Operations Center' video from the White House

Damage by Harvey on August 28, 2017

Texas

Houston Mayor Sylvester Turner imposed a mandatory curfew on August 29 from 12 a.m. to 5 a.m. local time until further notice. He cited looting as the primary reason for the curfew. On August 29, President Trump, First Lady Melania Trump, and U.S. Senators John Cornyn and Ted Cruz toured damage in the Corpus Christi metropolitan area. President Trump made a formal request for $5.95 billion in federal funding on August 31 for affected areas, the vast majority of which would go to FEMA.

Texas Governor Greg Abbott deployed the state's entire National Guard for search and rescue, recovery, and clean up operations due to the devastating damage caused by the storm and resulting floods. Other states' National Guard's have offered assistance, with several having already been sent. Meanwhile, the United States Immigration and Customs Enforcement assigned approximately 150 employees from around the country to assist with disaster relief efforts, while stating that no immigration enforcement operations would be conducted.

Approximately 32,000 people were displaced in shelters across the state by August 31. The George R. Brown Convention Center, the state's largest shelter, reached capacity with 8,000 evacuees. The NRG Center opened as a large public shelter accordingly. More than 210,000 people registered with FEMA for disaster assistance.

The Cajun Navy, an informal organization of volunteers with boats from Louisiana, deployed to Texas to assist in high-water rescues.

The Houston Independent School District announced that all students on any of the district's campuses would be eligible for free lunch throughout the 2017–18 school year. The Federal Department of Education eased financial aid rules and procedures for those affected by Harvey, giving schools the ability to waive paperwork requirements; loan borrowers were given more flexibility in managing their loan payments. A 36-year-old inmate sentenced to death for a 2003 murder was granted a temporary reprieve as a result of Harvey, as his legal team was based in Harris County, an area heavily affected by the hurricane.

By August 30, corporations across the nation collectively donated more than $72 million to relief efforts, with 42 companies donating at least $1 million. Professional athletic teams, their players, and managers provided large donations to assist victims of the storm. The Houston Astros pledged $4 million to relief along with all proceeds from their home game raffles. Houston Rockets owner Leslie Alexander also donated $4 million to the cause. A fundraiser established by Houston Texans defensive lineman J. J. Watt exceeded $10 million. The Texas Rangers and Tennessee Titans both provided $1 million, while the New England Patriots pledged to match up to $1 million in donations to the Red Cross. Multiple Hollywood celebrities also pitched in, collectively donating more than $10 million, with Sandra Bullock providing the largest single donation of $1 million. Leonardo DiCaprio provided $1 million to the United Way Harvey Recovery Fund through his foundation. Rachael Ray provided donations totaling $1 million to animal shelters across the Houston area.

Damage estimates

'Post-Harvey Rebuilding Expected to Cost More, Take Longer Because of Labor Shortage' video news report from Voice of America

A significant portion of the storm's damages may be uninsured losses. Regular homeowner insurance policies generally exclude coverage for flooding, as the National Flood Insurance Program underwrites most flood insurance policies in the US. Although the purchase of flood insurance is obligatory for federally guaranteed mortgages for homes within the 100-year flood plain, enforcement of the requirement is difficult and many homes, even within the 100-year flood plain, lack flood insurance. In Harris County, Texas—which includes the city of Houston—only 15% of homes have flood insurance policies issued by the NFIP. Participation in the NFIP is higher, but still low, in neighboring Galveston (41%), Brazoria (26%), and Chambers Counties (21%).

Preliminary estimates of economic losses range anywhere from $10 billion to $50 billion. Moody's Analytics has the estimate of between $40 billion to $50 billion in damages due to the storm. According to weather analytics firm Planalytics, lost revenue to Houston area retailers and restaurants alone will be approximately $1 billion. The Houston area controls 4% of the spending power in the United States.

Non-governmental organization response

The American Red Cross, Salvation Army, United States Equestrian Federation, Humane Society of the United States, Catholic Charities USA, AmeriCares, Operation BBQ relief, many celebrities, and many other charitable organizations provided help to the victims of the storm.

Volunteers from amateur radio's emergency service wing, the Amateur Radio Emergency Service, provided communications in American Red Cross shelters in South Texas.

Many corporations also contributed to relief efforts. Operation BBQ relief had the help from several local individuals and businesses kick off the support of providing meals for volunteers and victims. Smokers, pallets of wood, and another company came up with the pounds of pork to kick off the support effort. Although Operation BBQ relief has been in effect since May of 2011 with the 2011 Joplin tornado, they estimate that the Houston 2017 relief project to be their biggest ever.

Operation BBQ relief vendors volunteering for the Houston flood relief estimates that they will serve at least 450,000 meals. On August 27, 2017 it was estimated that Operation BBQ relief will be expecting 25,000 to 30,000 meals a day.

On August 27, 2017 KSL-TV, KSL Newsradio, FM100.3, and 103.5 The Arrow created a fundraiser to help Texas residents impacted by Hurricane Harvey. Because of an anonymous donor willing to match $2 for every $1 raised up to a total of $100,000, Peter Huntsman also agreed to match donations up to $100,000. The combined total of $200,000 was met by August 31, 2017. Their new goal is $1 million dollars.

Environmental factors

The Geography of Houston places it in a low-lying part of the Gulf Coastal Plain, and its clay-based soils provide poor drainage. The climate of Houston brings very heavy rainfall, which together with tidal flood events means that there have been repeated floods in the city ever since its founding in 1836, though the flood control district founded in 1947, aided by the U.S. Army Corps of Engineers, managed to prevent state-wide flooding for over fifty years. More recently, residents died in "historic flooding" in May 2015, and in the April 2016 "tax day floods". There is a tendency for storms to move very slowly over the region, and drop huge amounts of rain over an extended period, as occurred during Tropical Storm Claudette in 1979, and Tropical Storm Allison in 2001.

The area is a very flat flood plain at shallow gradient, slowly draining rainwater through an intricate network of channels and bayous to the sea. The main waterways, the San Jacinto River and the Buffalo Bayou, meander slowly, laden with mud, and have little capacity for carrying water.

Urban development

Houston has seen rapid uncontrolled urban development, with absorbent prairie and wetlands replaced by hard surfaces which rapidly shed storm water, overwhelming the drainage capacity of the rivers and channels.

The Katy Prairie in western Harris County, which once helped to absorb floodwaters in the region, has been reduced to one quarter of its previous size in the last several decades due to suburban development, and one analysis discovered that more than 7,000 housing units have been built within the 100-year floodplain in Harris County since 2010.

Subsidence

Extraction of oil and groundwater from underground aquifers leaves unsupported voids resulting in ground collapse, a process called subsidence. Houston itself is in a very large subsidence bowl, with smaller bowls within that area showing greater subsidence: in some cases as much as 9 feet (2.7 m). These result in drainage systems no longer having the required gradient to operate efficiently, so storm water drains more slowly. Areas affected by subsidence, such as Jersey Village, are among the worst affected by the flooding from Hurricane Harvey.

Climate change

See also: Tropical cyclone § Climate change

The Gulf of Mexico is known for hurricanes in August, so their incidence alone cannot be attributed to global warming, but the warming climate does influence certain attributes of storms. Studies in this regard show that storms tend to intensify rapidly prior to landfall. Weather events are due to multiple factors, and so cannot be said to be caused by one precondition, but climate change affects aspects of extreme events, and very likely worsened some of the impacts of Harvey. In a briefing, the World Meteorological Organization stated that the quantity of rainfall from Harvey had very likely been increased by climate change. The relationship between climate change and the frequency of hurricanes (or tropical cyclones) is still unclear, and is the subject of continuing research.

Harvey approached Houston over sea-surface waters which were significantly above average temperatures. Warm waters provide the main source of energy for hurricanes, and increased ocean heat can result in storms being larger, more intense and longer lasting, in particular bringing greatly increased rainfall. According to officials from the Harris County Flood Control District, Harvey caused the third '500-year' flood in three years. The National Climate Assessment states:

The recent increases in activity are linked, in part, to higher sea surface temperatures in the region that Atlantic hurricanes form in and move through. Numerous factors have been shown to influence these local sea surface temperatures, including natural variability, human-induced emissions of heat-trapping gases, and particulate pollution.

Warmer air can hold more water vapour, in accordance with the Clausius–Clapeyron relation, and there has been a global increase of daily rainfall records. Regional sea surface temperatures around Houston have risen around 0.5° C (0.9° F) in recent decades, which caused a 3–5% increase in moisture in the atmosphere. This had the effect of allowing Harvey to strengthen more than expected. The water temperature of the Gulf of Mexico was above average for this time of the year, and likely to be a factor in Harvey's impact.

The slow movement of Harvey over Texas allowed the storm to drop prolonged heavy rains on the state, as has also happened with earlier storms. Harvey's stalled position was due to weak prevailing winds linked to a greatly expanded subtropical high pressure system over much of the US at the time, which had pushed the jet stream to the north. Research and model simulations have indicated an association between this pattern and human-caused climate change.

Sea level rise

Sea level rise along the coast has combined the effects of global warming with subsidence mainly caused by extraction of oil and groundwater for water supplies, resulting in a sea level rise of 6 inches (15 cm) in recent decades.

See also

• List of Category 4 Atlantic hurricanes
• List of Texas hurricanes (1980–present)
• 2016 Louisiana floods  – Extensive rainfall resulted in widespread flooding across southern Louisiana, responsible for 13 deaths and billions in damage, despite not being a tropical cyclone

Other tropical cyclones with landfall in the same region of the Texas Gulf coast:

• 1886 Indianola hurricane – Destroyed the burgeoning port city of Indianola
• 1900 Galveston hurricane – Deadliest natural disaster in US history, impacting Galveston with unmitigated storm surge and killing as many as 12,000
• 1932 Freeport hurricane – Rapidly intensifying Category 4 hurricane that brought heavy rainfall to the Angleton and Freeport areas
• Hurricane Celia (1970) – Produced destructive winds in the Corpus Christi area
• Hurricane Bret (1999) – Made landfall on a relatively underpopulated stretch of the Texas coast, ending a decade-long period without a major hurricane landfall on the state
• Tropical Storm Allison (2001) – Caused significant flooding across same region of Texas Gulf Coast, 13th-costliest tropical cyclone in US history
• Hurricane Ike (2008) – Caused widespread destruction and flooding centered in the Galveston area, though Houston did not suffer flooding.

External links

• Hurricane Harvey Advisory Archive