Atlantic hurricane

An Atlantic hurricane or tropical storm is a tropical cyclone that forms in the Atlantic Ocean, usually between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis of location. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a cyclone occurs in the south Pacific or Indian Ocean. An Atlantic hurricane or tropical storm is a tropical cyclone that forms in the Atlantic Ocean, usually between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis of location. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a cyclone occurs in the south Pacific or Indian Ocean. Tropical cyclones can be categorized by intensity. Tropical storms have one-minute maximum sustained winds of at least 39 mph (34 knots, 17 m/s, 63 km/h), while hurricanes have one-minute maximum sustained winds exceeding 74 mph (64 knots, 33 m/s, 119 km/h). Most North Atlantic tropical storms and hurricanes form between June 1 and November 30. The United States National Hurricane Center monitors the basin and issues reports, watches, and warnings about tropical weather systems for the North Atlantic Basin as one of the Regional Specialized Meteorological Centers for tropical cyclones, as defined by the World Meteorological Organization. In recent times, tropical disturbances that reach tropical storm intensity are named from a predetermined list. Hurricanes that result in significant damage or casualties may have their names retired from the list at the request of the affected nations in order to prevent confusion should a subsequent storm be given the same name. On average, in the North Atlantic basin (from 1966 to 2009) 11.3 named storms occur each season, with an average of 6.2 becoming hurricanes and 2.3 becoming major hurricanes (Category 3 or greater). The climatological peak of activity is around September 10 each season. In March 2004, Catarina was the first hurricane-intensity tropical cyclone ever recorded in the Southern Atlantic Ocean. Since 2011, the Brazilian Navy Hydrographic Center has started to use the same scale of the North Atlantic Ocean for tropical cyclones in the South Atlantic Ocean and assign names to those which reach 35 kn (65 km/h; 40 mph). Tropical cyclones are steered by the surrounding flow throughout the depth of the troposphere (the atmosphere from the surface to about eight miles (12 km) high). Neil Frank, former director of the United States National Hurricane Center, used the analogies such as 'a leaf carried along in a stream' or a 'brick moving through a river of air' to describe the way atmospheric flow affects the path of a hurricane across the ocean. Specifically, air flow around high pressure systems and toward low pressure areas influences hurricane tracks. In the tropical latitudes, tropical storms and hurricanes generally move westward with a slight tendency toward the north, under the influence of the subtropical ridge, a high pressure system that usually extends east-west across the subtropics. South of the subtropical ridge, surface easterly winds (blowing from east to west) prevail. If the subtropical ridge is weakened by an upper trough, a tropical cyclone may turn poleward and then recurve, or curve back toward the northeast into the main belt of the Westerlies. Poleward (north) of the subtropical ridge, westerly winds prevail and generally steer tropical cyclones that reach northern latitudes toward the east. The westerlies also steer extratropical cyclones with their cold and warm fronts from west to east. Generally speaking, the intensity of a tropical cyclone is determined by either the storm's maximum sustained winds or lowest barometric pressure. The following table lists the most intense Atlantic hurricanes in terms of their lowest barometric pressure. In terms of wind speed, Hurricane Allen (in 1980) was the strongest Atlantic tropical cyclone on record, with maximum sustained winds of 190 mph (305 km/h). However, these measurements are suspect since instrumentation used to document wind speeds at the time would likely succumb to winds of such intensity. Nonetheless, their central pressures are low enough to rank them among the strongest recorded Atlantic hurricanes. Owing to their intensity, the strongest Atlantic hurricanes have all attained Category 5 classification. Hurricane Opal, the strongest Category 4 hurricane recorded, intensified to reach a minimum pressure of 916 mbar (hPa; 27.05 inHg), a pressure typical of Category 5 hurricanes. Nonetheless, the pressure remains too high to list Opal as one of the ten strongest Atlantic tropical cyclones. Presently, Hurricane Wilma is the strongest Atlantic hurricane ever recorded, after reaching an intensity of 882 mbar (hPa; 26.05 inHg) in October 2005; this also made Wilma the strongest tropical cyclone worldwide outside of the West Pacific, where seven tropical cyclones have been recorded to intensify to lower pressures. However, this was later superseded by Hurricane Patricia in 2015 in the east Pacific, which had a pressure reading of 872 mbar. Preceding Wilma is Hurricane Gilbert, which had also held the record for most intense Atlantic hurricane for 17 years. The 1935 Labor Day hurricane, with a pressure of 892 mbar (hPa; 26.34 inHg), is the third strongest Atlantic hurricane and the strongest documented tropical cyclone prior to 1950. Since the measurements taken during Wilma and Gilbert were documented using dropsonde, this pressure remains the lowest measured over land. Hurricane Rita is the fourth strongest Atlantic hurricane in terms of barometric pressure and one of three tropical cyclones from 2005 on the list, with the others being Wilma and Katrina at first and seventh respectively. However, with a barometric pressure of 895 mbar (hPa; 26.43 inHg), Rita is the strongest tropical cyclone ever recorded in the Gulf of Mexico. Mitch and Dean share intensities for the eighth strongest Atlantic hurricane at 905 mbar (hPa; 26.73 inHg). The tenth place for most intense Atlantic tropical cyclone is Hurricane Maria listed to have deepened to a pressure as low as 908 mbar (hPa; 26.81 inHg).