Tropical storm in the context of "Knot (unit)"

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 Wilma was the most intense tropical cyclone in the Atlantic basin and the second-most intense tropical cyclone in the Western Hemisphere, both based on barometric pressure, after Hurricane Patricia in 2015. Wilma's rapid intensification led to a 24-hour pressure drop of 97 mbar (2.9 inHg), setting a new basin record. At its peak, Hurricane Wilma's eye contracted to a record minimum diameter of 2.3 mi (3.7 km). In the record-breaking 2005 Atlantic hurricane season, Wilma was the twenty-second storm, thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane, and was the second costliest hurricane in Mexican history, behind Hurricane Otis in 2023.

Its origins came from a tropical depression that formed in the Caribbean Sea near Jamaica on October 15, headed westward, and intensified into a tropical storm two days later, which abruptly turned southward and was named Wilma. Continuing to strengthen, Wilma eventually became a hurricane on October 18. Shortly thereafter, explosive intensification occurred, and in only 24 hours, Wilma became a Category 5 hurricane with wind speeds of 185 mph (295 km/h). Wilma's intensity slowly leveled off after becoming a Category 5 hurricane, and winds had decreased to 150 mph (240 km/h) before it reached the Yucatán Peninsula on October 20 and 21. After crossing the Yucatán, Wilma emerged into the Gulf of Mexico as a Category 2 hurricane. As it began accelerating to the northeast, gradual re-intensification occurred, and the hurricane was upgraded to Category 3 status on October 24. Shortly thereafter, Wilma made landfall in Cape Romano, Florida, with winds of 120 mph (190 km/h). As Wilma was crossing Florida, it briefly weakened back to a Category 2 hurricane, but again re-intensified as it reached the Atlantic Ocean. The hurricane intensified into a Category 3 hurricane for the last time, before weakening while accelerating northeastward. By October 26, Wilma transitioned into an extratropical cyclone southeast of Nova Scotia.

A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice and snow. Flash floods may also occur after the collapse of a natural ice or debris dam, or a human structure such as a man-made dam, as occurred before the Johnstown Flood of 1889. Flash floods are distinguished from regular floods by having a timescale of fewer than six hours between rainfall and the onset of flooding.

Flash floods are a significant hazard, causing more fatalities in the U.S. in an average year than lightning, tornadoes, or hurricanes. They can also deposit large quantities of sediments on floodplains and destroy vegetation cover not adapted to frequent flood conditions.

The Saffir–Simpson hurricane wind scale (SSHWS) is a tropical cyclone intensity scale that classifies hurricanes—which in the Western Hemisphere are tropical cyclones that exceed the intensities of tropical depressions and tropical storms—into five categories distinguished by the intensities of their sustained winds. This measuring system was formerly known as the Saffir–Simpson hurricane scale, or SSHS.

To be classified as a hurricane, a tropical cyclone must have one-minute-average maximum sustained winds at 10 m (33 ft) above the surface of at least 74 mph (64 kn, 119 km/h; Category 1). The highest classification in the scale, Category 5, consists of storms with sustained winds of at least 157 mph (137 kn, 252 km/h). The classifications can provide some indication of the potential damage and flooding a hurricane will cause upon landfall.

South Atlantic tropical cyclones are unusual weather events that occur in the Southern Hemisphere. Strong wind shear, which disrupts the formation of cyclones, as well as a lack of weather disturbances favorable for development in the South Atlantic Ocean, make any strong tropical system extremely rare, and Hurricane Catarina in 2004 is the only recorded South Atlantic hurricane in history. Storms can develop year-round in the South Atlantic, with activity peaking during the months from November through May. Since 2011, the Brazilian Navy Hydrographic Center has assigned names to tropical and subtropical systems in the western side of the basin, near the eastern coast of Brazil, when they have sustained wind speeds of at least 65 km/h (40 mph), the generally accepted minimum sustained wind speed for a disturbance to be designated as a tropical storm in the North Atlantic basin. Below is a list of notable South Atlantic tropical and subtropical cyclones.