The classification Atlantic tropical storm is used to refer to a tropical cyclone that forms in the North Atlantic Ocean with 1-minute maximum sustained wind speeds from 39 mph (63 km/h) to 72 mph (117 km/h). Tropical cyclones that attain such winds and move over land while maintaining those winds are capable of causing minor to moderate damage to human lives and infrastructure. Since the Atlantic hurricane database (HURDAT) began in 1851, there have been 761 tropical storms recorded, as well as 92 others not recognized by HURDAT, but recognized by the International Best Track Archive for Climate Stewardship (IBTrACS) as possible tropical storms, in the North Atlantic tropical cyclone basin, which is denoted as the part of the Atlantic Ocean north of the equator. This list does not include tropical storms that later intensified into hurricanes. The development of tropical storms in the North Atlantic basin is influenced by many factors. During the Northern Hemisphere winter and spring months of December to April, sea surface temperatures in the tropics are usually too low to support tropical cyclogenesis, and there are multiple high-pressure systems, such as the Azores High, that also inhibit tropical cyclogenesis. These effects are reduced or even disappear during hurricane season from May to November, when sea surface temperatures are also high enough to support tropical cyclogenesis; the bulk of recorded tropical storms developed during June to November. Global weather patterns may also influence hurricane development in the North Atlantic. El Niño events result in reduced numbers of powerful hurricanes through stronger wind shear and lower sea surface temperatures within the basin, while La Niña events increase the number of such hurricanes through the opposite.
Background
On the Saffir–Simpson scale, a tropical cyclone reaches tropical storm status when it attains maximum sustained winds of between 34 knots (39 mph; 63 km/h; 17 m/s) and 63 knots (72 mph; 117 km/h; 32 m/s). The National Hurricane Center (NHC) defines sustained winds as the average wind speed measured over the period of one minute at the height of 10 metres (33 ft) above the ground. Should a tropical storm make landfall, its strongest winds are not especially damaging, and are unlikely to cause damage to any sturdy structure, but can often make trees and their branches fall. A larger danger is a tropical storm's rainfall, which can cause major flooding, as in the case of Tropical Storm Allison, and a slow-moving system can cause severe loss of life. The North Atlantic tropical cyclone basin is defined as the region of the Atlantic Ocean north of the equator, while other boundaries are mainly established by land areas. The main bodies of water included in the Atlantic basin are the North Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea. Storms that form in the South Atlantic Ocean or in the Mediterranean Sea are not part of the Atlantic basin. The Regional Specialized Meteorological Center (RSMC) for the North Atlantic basin is the NHC, which manages the warnings of tropical cyclones there. On average from 1980 to 2024, an average of 13.6 storms of at least tropical storm strength form in one year, though the number can range from only four in 1983 to thirty in 2020. Of these storms, 6.9 reach hurricane intensity; meaning that 6.7 peak as tropical storms. All tropical cyclones recorded by past and present RSMCs of the North Atlantic basin since 1851 are listed in the North Atlantic hurricane database (HURDAT), which is compiled and maintained by the National Hurricane Center.
Climatology
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