![]() Owing to their intensity, the strongest Atlantic hurricanes have all attained Category 5 classification. Nonetheless, their central pressures are low enough to rank them among the strongest recorded Atlantic hurricanes. However, these measurements are suspect since instrumentation used to document wind speeds at the time would likely succumb to winds of such intensity. 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). The following table lists the most intense Atlantic hurricanes in terms of their lowest barometric pressure. ![]() Generally speaking, the intensity of a tropical cyclone is determined by either the storm's maximum sustained winds or lowest barometric pressure. The westerlies also steer extratropical cyclones with their cold and warm fronts from west to east. Poleward (north) of the subtropical ridge, westerly winds prevail and generally steer tropical cyclones that reach northern latitudes toward the east. 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. South of the subtropical ridge, surface easterly winds (blowing from east to west) prevail. 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. Specifically, air flow around high pressure systems and toward low-pressure areas influences hurricane tracks. 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. Tropical cyclones are steered by the surrounding flow throughout the depth of the troposphere (the atmospheric from the surface to about eight miles (13 km) high). The subtropical ridge (in the Pacific) shows up as a large area of black (dryness) on this water vapor satellite image from September 2000 ![]() Since 2011, the Brazilian Navy Hydrographic Center has started to use the same scale as 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). In March 2004, Catarina was the first hurricane-intensity tropical cyclone to be recorded in the Southern Atlantic Ocean. The climatological peak of activity is around September 10 each season. ![]() 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). 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. In recent times, tropical disturbances that reach tropical storm intensity are named from a predetermined list. 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. Most North Atlantic tropical storms and hurricanes form between June 1 and November 30. 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). Tropical cyclones can be categorized by intensity. 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 Ocean or Indian Ocean. A hurricane differs from a cyclone or typhoon only on the basis of location. ![]() An Atlantic hurricane, also known as tropical storm or simply hurricane, is a tropical cyclone that forms in the Atlantic Ocean, primarily between the months of June and November. ![]()
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