Rapid intensification in the context of "Tropical cyclones and climate change"

Hurricane Harvey was a powerful and devastating tropical cyclone that made landfall in Texas and Louisiana in August 2017, causing catastrophic flooding and more than 100 deaths. It is tied with 2005's Hurricane Katrina as the costliest tropical cyclone on record, inflicting $125 billion (2017 USD) in damage, primarily from catastrophic rainfall-triggered flooding in Greater Houston and Southeast Texas; this made the storm the costliest natural disaster recorded in Texas at the time. It was the first major hurricane to make landfall in the United States since Wilma in 2005, ending a record 12-year span in which no hurricanes made landfall at the intensity of a major hurricane throughout the country. In a four-day period, many areas received more than 40 inches (1,000 mm) of rain as the system slowly meandered over eastern Texas and adjacent waters, causing unprecedented flooding. With peak accumulations of 60.58 in (1,539 mm) in Nederland, Texas, Harvey was the wettest tropical cyclone on record in the United States. The resulting floods inundated hundreds of thousands of homes, which displaced more than 30,000 people and prompted more than 17,000 rescues.

The eighth named storm, third hurricane, and first major hurricane of the extremely active 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, making landfall on the southern end of Barbados and a second landfall on Saint Vincent. Upon entering the Caribbean, Harvey began to weaken due to moderate wind shear, and degenerated into a tropical wave north of Colombia, late 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.

Hurricane Marie is tied as the seventh-most intense Pacific hurricane on record, attaining a barometric pressure of 918 mbar (hPa; 27.11 inHg) in August 2014. The fourteenth named storm, ninth hurricane, and sixth major hurricane of the season, Marie began as a tropical wave that emerged off the west coast of Africa over the Atlantic Ocean on August 10. Some organization of shower and thunderstorm activity initially took place, but dry air soon impinged upon the system and imparted weakening. The wave tracked westward across the Atlantic and Caribbean for several days. On August 19, an area of low pressure consolidated within the wave west of Central America. With favorable atmospheric conditions, convective activity and banding features increased around the system and by August 22, the system acquired enough organization to be classified as Tropical Depression Thirteen-E while situated about 370 mi (595 km) south-southeast of Acapulco, Mexico. Development was initially fast-paced, as the depression acquired tropical storm-force winds within six hours of formation and hurricane-force by August 23. However, due to some vertical wind shear its intensification rate stalled, and for a time it remained a Category 1 hurricane on the Saffir–Simpson hurricane wind scale.

On August 24, Marie developed an eye and rapidly intensified to a Category 5 hurricane with winds of 160 mph (260 km/h). At its peak, the hurricane's gale-force winds spanned an area 575 mi (925 km) across. Marie subsequently underwent an eyewall replacement cycle on August 25 which prompted steady weakening. Over the next several days, Marie progressively degraded to below hurricane strength as it moved into an increasingly hostile environment with cooler waters and a more stable atmosphere. On August 29, after having lost all signs of organized deep convection, Marie degenerated into a remnant low. The large system gradually wound down over the following several days, with winds subsiding below gale-force on August 30. The remnant cyclone eventually lost a well defined center and dissipated on September 2 about 1,200 mi (1,950 km) northeast of Hawaii.

Hurricane Katrina was an extremely powerful and catastrophic tropical cyclone that killed 1,392 people and caused damage estimated at $125 billion, particularly in and around the city of New Orleans, in late August 2005. 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, the third major hurricane, and the second Category 5 hurricane of the 2005 Atlantic hurricane season. It was also the fourth-most intense Atlantic hurricane to make landfall in the contiguous United States, as measured by barometric pressure.

Katrina formed on August 23, 2005, with the merger of a tropical wave and the remnants of a tropical depression. After briefly strengthening to a tropical storm over south Florida, Katrina entered the Gulf of Mexico on August 26 and rapidly intensified to a Category 5 hurricane before weakening to a Category 3 at its landfall on August 29 near Buras-Triumph, Louisiana.

Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale.

• Tropical cyclones form due to latent heat driven by significant thunderstorm activity, developing a warm core.
• Extratropical cyclones form as waves along weather fronts before occluding later in their life cycle as cold core cyclones.
• Mesocyclones form as warm core cyclones over land, and can lead to tornado formation. Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear.

The process in which an extratropical cyclone undergoes a rapid drop in atmospheric pressure (24 millibars or more) in a 24-hour period is referred to as explosive cyclogenesis, and is usually present during the formation of a nor'easter. Similarly, a tropical cyclone can undergo rapid intensification.

Hurricane Florence was a powerful and long-lived tropical cyclone that caused catastrophic damage in the Carolinas in September 2018, primarily as a result of freshwater flooding due to torrential rain. The sixth named storm, third hurricane, and the first major hurricane of the 2018 Atlantic hurricane season, Florence originated from a strong tropical wave that emerged off the west coast of Africa on August 30, 2018. The wave steadily organized, and strengthened into a tropical depression on the next day near Cape Verde. Progressing along a steady west-northwest trajectory, the system gradually strengthened, acquiring tropical storm strength on September 1. An unexpected bout of rapid intensification ensued on September 4–5, culminating with Florence becoming a Category 4 major hurricane on the Saffir–Simpson scale (SSHWS), with estimated maximum sustained winds of 130 mph (215 km/h). Strong wind shear then led to rapid weakening, and Florence weakened to tropical storm strength on September 7. Shifting steering currents led to a westward turn into a more suitable environment; as a result, Florence reintensified to hurricane strength on September 9 and major hurricane status by the following day. Florence reached peak intensity on September 11, with 1-minute winds of 150 mph (240 km/h) and a minimum central pressure of 937 mbar (27.7 inHg). An unexpected eyewall replacement cycle and decreasing oceanic heat content caused a steady weakening trend; however, the storm grew in size at the same time. Early on September 14, Florence made landfall in the United States just south of Wrightsville Beach, North Carolina as a Category 1 hurricane, and weakened further as it slowly moved inland under the influence of weak steering currents. Florence degenerated into a post-tropical cyclone over West Virginia on September 17 and was absorbed by another frontal storm two days later.

Early in the storm's history, the system brought squalls to the Cape Verde islands, resulting in minor landslides and flooding; however, overall effects remained negligible. With the threat of a major impact in the Southeastern and Mid-Atlantic United States becoming evident by September 7, the governors of North Carolina, South Carolina, Virginia, Georgia, and Maryland, and the mayor of Washington, D.C. declared a state of emergency. On September 10 and 11, the states of North Carolina, South Carolina, and Virginia issued mandatory evacuation orders for some of their coastal communities, predicting that emergency personnel would be unable to reach people there once the storm arrived. Though Florence made landfall as a greatly weakened Category 1 hurricane, winds associated with the tropical cyclone were strong enough to uproot trees and power lines, causing extensive power outages across the Carolinas. Furthermore, due to the slow motion of the storm, heavy rain fell throughout the Carolinas for several days. Coupled with a powerful storm surge, the rainfall caused widespread flooding along a long stretch of the North Carolina coast, from New Bern to Wilmington. Inland flooding from Florence inundated cities such as Fayetteville, Smithfield, Lumberton, Durham, and Chapel Hill. Most major roads and highways in the area experienced flooding, with large stretches of I-40, I-95, and US Route 70 remaining impassable for days after the storm's passage. Wilmington was cut off entirely from the rest of the mainland by the flooding. The storm also spawned tornadoes in several places along its path, including an EF2 tornado that killed one person in Virginia. Many places received record-breaking rainfall, with Florence setting maximum rainfall records from a tropical cyclone in both of the Carolinas. Overall, the storm caused $24.23 billion in damage, mostly in the Carolinas, and 54 deaths.

Typhoon Noru was the second-longest-lasting tropical cyclone of the Northwest Pacific Ocean on record—behind only 1986's Wayne and tied with 1972's Rita—and the second-most-intense tropical cyclone of the basin in 2017, tied with Talim, just behind Lan. Forming as the fifth named storm of the annual typhoon season on July 20, Noru further intensified into the first typhoon of the year on July 23. However, Noru began to interact with nearby Tropical Storm Kulap on July 24, executing a counterclockwise loop southeast of Japan. Weakening to a severe tropical storm on July 28, Noru began to restrengthen as it turned sharply to the west on July 30. Amid favorable conditions, Noru rapidly intensified into the season's first super typhoon, and reached peak intensity with annular characteristics on July 31. In early August, Noru underwent a gradual weakening trend while curving northwestwards and then northwards. After stalling off the Satsunan Islands weakening to a severe tropical storm again on August 5, the system began to accelerate northeastwards towards the Kansai region of Japan, making landfall in Wakayama Prefecture on August 7. Noru became extratropical over the Sea of Japan on August 8, and dissipated one day later.

Noru was responsible for two deaths in Kagoshima Prefecture, and at least $100 million (2017 USD) in damages in Japan.

Hurricane Irma was an extremely powerful and devastating tropical cyclone that caused extensive damage and loss of life across the Antilles and Eastern United States in September 2017. Irma was the first Category 5 hurricane to strike the Leeward Islands on record, though it was followed by Hurricane Maria, which struck the region at Category 5 intensity as well two weeks later. At the time, Irma was considered the most powerful hurricane on record in the open Atlantic region, outside of the Caribbean Sea and Gulf of Mexico, until it was surpassed by Hurricane Dorian two years later. It was also the third-strongest Atlantic hurricane at landfall ever recorded, just behind the 1935 Labor Day hurricane, Hurricane Melissa, and Dorian.

The ninth named storm, fourth hurricane, second major hurricane, and first Category 5 hurricane of the extremely active 2017 Atlantic hurricane season, Irma developed from a tropical wave near the Cape Verde Islands on August 30. Favorable conditions allowed Irma to rapidly intensify into a Category 3 hurricane on the Saffir–Simpson wind scale by late on August 31. The storm's intensity fluctuated between Categories 2 and 3 for the next several days, due to a series of eyewall replacement cycles. On September 4, Irma resumed intensifying, becoming a Category 5 hurricane by early on the next day. Early on September 6, Irma peaked with 1-minute sustained winds of 180 mph (290 km/h) and a minimum pressure of 914 hPa (27.0 inHg). Irma was the second-most intense tropical cyclone worldwide in 2017 in terms of barometric pressure, and the strongest worldwide in 2017 in terms of wind speed. Another eyewall replacement cycle caused Irma to weaken back to a Category 4 hurricane, but the storm re-attained Category 5 status before making landfall in Cuba. Although Irma briefly weakened to a Category 2 storm while making landfall on Cuba, the system re-intensified to Category 4 status as it crossed the warm waters of the Straits of Florida, before making landfall on Cudjoe Key on September 10. Irma then weakened to Category 3 status, prior to another landfall in Florida on Marco Island later that day. The system degraded into a remnant low over Alabama and ultimately dissipated on September 13 over Missouri.

Hurricane Maria was an extremely powerful and catastrophic tropical cyclone that affected the northeastern Caribbean in September 2017, particularly in the U.S. territory of Puerto Rico, which accounted for 2,975 of the 3,059 deaths. It is the deadliest and costliest hurricane to strike the archipelago and island of Puerto Rico, and is the deadliest hurricane to strike the country of Dominica and the territory of the U.S. Virgin Islands. The most intense tropical cyclone worldwide in 2017, Maria was the thirteenth named storm, eighth consecutive hurricane, fourth major hurricane, second Category 5 hurricane, and deadliest storm of the extremely active 2017 Atlantic hurricane season. With over 3,000 deaths and a minimum central pressure of 908 millibars (26.8 inHg), Maria was the twelfth most intense Atlantic hurricane on record, respectively. Total monetary losses are estimated at upwards of $91.61 billion (2017 USD), almost all of which came from Puerto Rico, ranking it as the fourth-costliest tropical cyclone on record.

Maria developed from a tropical wave on September 16 east of the Lesser Antilles. Steady strengthening and organization took place initially, until favorable conditions enabled it to undergo explosive intensification on the afternoon of September 18, achieving Category 5 strength just before making landfall on the island of Dominica that night. After crossing the island and weakening slightly, Maria re-intensified and achieved its peak intensity with maximum sustained winds of 175 mph (280 km/h) and a pressure of 908 mbar (hPa; 26.81 inHg). On September 20, an eyewall replacement cycle weakened Maria to a high-end Category 4 hurricane by the time it struck Puerto Rico. The hurricane re-emerged weaker from land interaction, but quickly restrengthened back into a major hurricane again the following day. Passing north of The Bahamas, Maria remained a powerful hurricane over the following week as it slowly paralleled the East Coast of the United States, gradually weakening over time as conditions became less favorable. Maria then stalled and swung eastward over the open Atlantic, becoming extratropical on September 30 before dissipating by October 2.