query: in the southern hemisphere what is the direction of surface wind movement about a tropical cyclone

pos: Cyclone cyclone would collapse on itself as a result of the difference in pressure. Because of the Coriolis effect, the wind flow around a large cyclone is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. In the Northern Hemisphere, the fastest winds relative to the surface of the Earth therefore occur on the eastern side of a northward-moving cyclone and on the northern side of a westward-moving one; the opposite occurs in the Southern Hemisphere. In contrast to low pressure systems, the wind flow around high pressure systems are clockwise (anticyclonic) in the northern hemisphere, and counterclockwise in

pos: Tropical cyclone simply as "tropical cyclones" or "severe cyclonic storms". "Tropical" refers to the geographical origin of these systems, which form almost exclusively over tropical seas. "Cyclone" refers to their winds moving in a circle, whirling round their central clear eye, with their winds blowing counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. The opposite direction of circulation is due to the Coriolis effect. Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface, which ultimately recondenses into clouds and rain when moist air rises

pos: Mesoscale convective system The term "cyclone" refers to such storms' cyclonic nature, with counterclockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on their location and strength, tropical cyclones are referred to by other names, such as hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, or simply as a cyclone. Generally speaking, a tropical cyclone is referred to as a hurricane (from the name of the ancient Central American deity of wind, Huracan) in the Atlantic and eastern Pacific oceans, a typhoon across the northwest Pacific ocean, and a cyclone across in the southern hemisphere and Indian ocean.

pos: Tropical cyclone track forecasting while northeast moving storms move slower and left. The larger the cyclone, the larger the impact of the beta effect is likely to be. When two or more tropical cyclones are in proximity to one another, they begin to rotate cyclonically around the midpoint between their circulation centers. In the northern hemisphere, this is in a counterclockwise direction, and in the southern hemisphere, a clockwise direction. Usually, the tropical cyclones need to be within of each other for this effect to take place. It is a more common phenomenon in the northern Pacific Ocean than elsewhere, due to the higher

pos: Cyclone sub-polar, or Arctic cyclone (also known as a polar vortex) is a vast area of low pressure that strengthens in the winter and weakens in the summer. A polar cyclone is a low-pressure weather system, usually spanning to , in which the air circulates in a counterclockwise direction in the northern hemisphere, and a clockwise direction in the southern hemisphere. The Coriolis acceleration acting on the air masses moving poleward at high altitude, causes a counterclockwise circulation at high altitude. The poleward movement of air originates from the air circulation of the Polar cell. The polar low is not driven

pos: Anticyclone Anticyclone An anticyclone (that is, opposite to a cyclone) is a weather phenomenon defined by the United States National Weather Service's glossary as "a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere". Effects of surface-based anticyclones include clearing skies as well as cooler, drier air. Fog can also form overnight within a region of higher pressure. Mid-tropospheric systems, such as the subtropical ridge, deflect tropical cyclones around their periphery and cause a temperature inversion inhibiting free convection near their center, building up surface-based haze under their

pos: Cyclone the geographic origin of these systems, which form almost exclusively in tropical regions of the globe, and their dependence on Maritime Tropical air masses for their formation. The term "cyclone" refers to the storms' cyclonic nature, with counterclockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on their location and strength, tropical cyclones are referred to by other names, such as hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, or simply as a cyclone. While tropical cyclones can produce extremely powerful winds and torrential rain, they are also able to produce high waves and a

neg: Tropical cyclone scales cyclones are defined as being warm cored, non-frontal synoptic cyclones, that develop over tropical or subtropical waters, with organized atmospheric convection and have a definite cyclonic surface wind circulation. They are classified by the wind speeds located around the circulation centre and are ranked, by the World Meteorological Organisation's Regional Specialized Meteorological Centers on one of five tropical cyclone scales. The scale used for a particular tropical cyclone depends on what basin the system is located in; with for example the Saffir–Simpson hurricane wind scale and the Australian tropical cyclone intensity scales both used in the Western Hemisphere. All of

neg: Effects of tropical cyclones have a way to safely navigate around tropical cyclones. They split tropical cyclones in two, based on their direction of motion, and maneuver to avoid the right segment of the cyclone in the Northern Hemisphere (the left segment in the Southern Hemisphere). Sailors term the right side the dangerous semicircle since the heaviest rain and strongest winds and seas were located in this half of the storm, as the cyclone's translation speed and its rotational wind are additive. The other half of the tropical cyclone is called the navigable semicircle since weather conditions are lessened (subtractive) in this portion of

neg: Australian region tropical cyclone runs from 1 November to 30 April. Three of the warning centres are. Australian region tropical cyclone An Australian tropical cyclone is a non frontal, low pressure system that has developed, within an environment of warm sea surface temperatures and little vertical wind shear aloft in either the Southern Indian Ocean or the South Pacific Ocean. Within the Southern Hemisphere there are officially three areas where tropical cyclones develop on a regular basis, these areas are the South-West Indian Ocean between Africa and 90°E, the Australian region between 90°E and 160°E and the South Pacific basin between 160°E and 120°W.

neg: Australian region tropical cyclone Australian region tropical cyclone An Australian tropical cyclone is a non frontal, low pressure system that has developed, within an environment of warm sea surface temperatures and little vertical wind shear aloft in either the Southern Indian Ocean or the South Pacific Ocean. Within the Southern Hemisphere there are officially three areas where tropical cyclones develop on a regular basis, these areas are the South-West Indian Ocean between Africa and 90°E, the Australian region between 90°E and 160°E and the South Pacific basin between 160°E and 120°W. The Australian region between 90°E and 160°E is officially monitored by the Australian

neg: Tropical cyclone the surroundings at all altitudes, thus they are characterized as "warm core" systems. The near-surface wind field of a tropical cyclone is characterized by air rotating rapidly around a center of circulation while also flowing radially inwards. At the outer edge of the storm, air may be nearly calm; however, due to the Earth’s rotation, the air has non-zero absolute angular momentum. As air flows radially inward, it begins to rotate cyclonically (counter-clockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere) in order to conserve angular momentum. At an inner radius, air begins to ascend to the top

neg: South Pacific tropical cyclone South Pacific tropical cyclone A South Pacific tropical cyclone is a non frontal, low pressure system that has developed, within an environment of warm sea surface temperatures and little vertical wind shear aloft in the South Pacific Ocean. Within the Southern Hemisphere there are officially three areas where tropical cyclones develop on a regular basis, these areas are the South-West Indian Ocean between Africa and 90°E, the Australian region between 90°E and 160°E and the South Pacific basin between 160°E and 120°W. The South Pacific basin between 160°E and 120°W is officially monitored by the Fiji Meteorological Service and New

neg: Pressure system acquires a well-defined circulation in the tropics it is termed a tropical cyclone. Tropical cyclones can form during any month of the year globally, but can occur in either the northern hemisphere or the southern hemisphere during November. Atmospheric lift caused by low-level wind convergence into the surface low brings clouds and potentially precipitation. The low-pressure area's cloudy skies act to minimize diurnal temperature variation. Since clouds reflect sunlight, incoming shortwave solar radiation is less, which causes lower temperatures during the day. At night, the absorptive effect of clouds on outgoing longwave radiation, such as heat energy from the surface,

neg: Cyclone Viyaru excellent poleward outflow, and unusually high sea surface temperatures (estimated at ), the system was anticipated to become a tropical cyclone over the following days. A pulse in the Madden–Julian oscillation, coupled with a convective Kelvin wave allowed the system, along with its Southern Hemisphere counterpart Tropical Storm Jamala, to further develop. Following additional organization, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert for the low on May 10. Despite an increase in wind shear, causing the low to become dislocated from the deepest convection, the system further intensified and a scatterometer pass from the Oceansat-2

neg: 1996 North Indian Ocean cyclone season 2010. In early May, a westerly wind burst spawned two disturbances on both sides of the equator in the eastern Indian Ocean, in association with the monsoon trough. The system in the southern hemisphere eventually became Tropical Storm Jenna, while the system in the northern hemisphere developed an area of convection about 445 km (275 mi) northwest of Sumatra. This disturbance moved generally northward, and initially remained disorganized; the thunderstorms were removed from the circulation. However, the JTWC issued a Tropical cyclone formation alert (TCFA) on May 5 once the system became better organized amid low wind shear. Rounding the

neg: South Atlantic tropical cyclone "Kurumí" in 2018 without being used. There have been over 77 recorded tropical and subtropical cyclones in the South Atlantic Ocean since 1957. Like most southern hemisphere cyclone seasons, most of the storms have formed between November and May. List of storms, by month List of storms, by decade South Atlantic tropical cyclone 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

neg: Tropical cyclone scales cyclones originating in the Arabian Sea are assigned suffix "A" while those in the Bay of Bengal get suffix "B"). These warnings use a 1-minute sustained wind speed and can be compared to the Saffir–Simpson hurricane wind scale, however, regardless of intensity in this basin the JTWC labels all systems as tropical cyclones with TC numbers (optionally appended with intl. names/placeholders in parentheses, as done for typhoons above). Any tropical cyclone that develops within the Southern Hemisphere between Africa and 90°E is monitored by Meteo France's La Reunion tropical cyclone centre (MFR, RSMC La Reunion). Within the region a tropical

neg: Tropical cyclone scales of . Tropical cyclones that occur within the Northern Hemisphere between the anti-meridian and 100°E, are officially monitored by the Japan Meteorological Agency (JMA, RSMC Tokyo). Within the region a tropical cyclone is defined to be a non-frontal synoptic scale cyclone originating over tropical or sub-tropical waters, with organized convection and a definite cyclonic surface wind circulation. The lowest classification used by the Typhoon Committee is a tropical depression, which has 10-minute sustained winds of less than . Should the tropical depression intensify further it is named and classified as a tropical storm, which has winds speeds between . Should

neg: Cyclone Zoe before it was declared extratropical as it interacted with an extratropical low which was located over the Tasman Sea. Zoe was subsequently last noted by the FMS during January 4, while it was located about to the southeast of Noumea, New Caledonia. At its peak intensity Zoe was estimated by the FMS to be a Category 5 severe tropical cyclone, with 10-minute sustained wind speeds of 240 km/h (150 mph) and a minimum pressure of . Zoe was the most intense tropical cyclone in the Southern Hemisphere until a 2017 reanalysis of Cyclone Winston estimated a minimum pressure of ,

neg: Cyclone Bella any Southern Hemisphere storm during the tropical cyclone year. On January 30, Bella turned to the southeast and began weakening, affected by wind shear in the region. The cyclone passed about 50 km (30 mi) west of Rodrigues at 03:00 UTC on January 31, with 10 minute winds of 135 km/h (85 mph). Shortly thereafter, the cyclone deteriorated into a tropical storm. The southeast trajectory was short-lived, as Bella turned more to the south-southwest on February 1. After a final turn to the southeast, Bella became an extratropical cyclone on February 4. Before Bella affected land, a class one warning,

neg: Cyclone Betsy Cyclone Betsy Severe Tropical Cyclone Betsy impacted 8 island nations. In early January 1992, an equatorial westerly wind burst caused a surge of stronger than normal low level westerly winds, to develop on the northern side of the Southern Hemisphere monsoon trough to the east of New Guinea. Enhanced convection associated with the wind burst gradually became more organized and by late on January 5, a tropical depression had developed within the monsoon trough to the west of Tuvalu. Early on January 6, the JTWC initiated advisories on the depression and designated it as Tropical Cyclone 11P, as it moved

neg: Tropical cyclone naming sustained wind speeds of more than . However, standards vary from basin to basin, with some systems named in the Western Pacific when they develop into tropical depressions or enter PAGASA's area of responsibility. Within the Southern Hemisphere, systems must be characterized by a significant amount of gale-force winds occurring around the center before they are named. Any member of the World Meteorological Organization's hurricane, typhoon and tropical cyclone committees can request that the name of a tropical cyclone be retired or withdrawn from the various tropical cyclone naming lists. A name is retired or withdrawn if a consensus or

neg: Upwelling and the most closely related to human activities as it supports some of the most productive fisheries in the world. Wind-driven currents are diverted to the right of the winds in the Northern Hemisphere and to the left in the Southern Hemisphere due to the Coriolis effect. The result is a net movement of surface water at right angles to the direction of the wind, known as the Ekman transport (See also Ekman Spiral). When Ekman transport is occurring away from the coast, surface waters moving away are replaced by deeper, colder, and denser water. Normally, this upwelling process occurs

neg: Sea circular movement of surface currents known as a gyre is formed. There are five main gyres in the world's oceans: two in the Pacific, two in the Atlantic and one in the Indian Ocean. Other smaller gyres are found in lesser seas and a single gyre flows around Antarctica. These gyres have followed the same routes for millennia, guided by the topography of the land, the wind direction and the Coriolis effect. The surface currents flow in a clockwise direction in the Northern Hemisphere and anticlockwise in the Southern Hemisphere. The water moving away from the equator is warm, and

neg: 1989–90 South Pacific cyclone season designated tropical cyclones with a number and a P suffix with numbers assigned in order to tropical cyclones developing within the whole of the Southern Hemisphere. TCWC Nadi, TCWC Wellington and TCWC Brisbane all use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a ten-minute period, while the JTWC estimates sustained winds over a one-minute period, which are subsequently compared to the Saffir–Simpson hurricane wind scale (SSHWS). On December 19, the remnants of Tropical Cyclone Felicity, moved into the basin with 10-minute sustained windspeeds of 75 km/h (45 mph), which would have made it a category 1

neg: Tropical cyclone conditions on land within 48 hours, then it will be classified by the NHC, CPHC, or JTWC as a potential tropical cyclone (PTC). A tropical depression or tropical low is a tropical disturbance that has a clearly defined surface circulation with maximum sustained winds of less than . Within the Southern Hemisphere, the depression can have gale force or stronger winds in one or more quadrants, but not near the centre. A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds between and . At this point, the distinctive cyclonic shape

neg: Cyclone Tracy features such as newsreel footage of the devastation and a documentary titled "On A Wind And A Prayer". Cyclone Tracy Cyclone Tracy was a tropical cyclone that from Christmas Eve to Christmas Day, 1974, devastated the city of Darwin, Northern Territory, Australia. It is the most compact cyclone or equivalent-strength hurricane on record in the Australian basin and Southern Hemisphere, with gale-force winds extending only from the centre, and was also the smallest tropical cyclone worldwide until 2008, when Tropical Storm Marco of the 2008 Atlantic hurricane season broke the record, with gale-force winds extending only from the centre. After

neg: Pre-1970 Southern Hemisphere tropical cyclone seasons Pre-1970 Southern Hemisphere tropical cyclone seasons The Pre-1970 Southern Hemisphere tropical cyclone seasons ran year-round from July 1 to June 30, reaching their peaks mid-February to early March. For storms in the South-West Indian Ocean, see here. The Banda Islands were hit in March. The cyclone blew the roof off of almost every house and killed 85% of nutmeg trees. A tropical cyclone hit the Banda Islands. A cyclone hit the island of Roti in April, killing 75 and destroying many homes. Around this time, a tropical cyclone hit the Kei Islands, uprooting many trees. On 20 April 1872, a

neg: Marine weather forecasting Hemisphere (the left in the Southern Hemisphere). Sailors term the right side the dangerous semicircle since the heaviest rain and strongest winds and seas were located in this half of the storm, as the cyclone's translation speed and its rotational wind are additive. The other half of the tropical cyclone is called the navigable semicircle since weather conditions are lessened (subtractive) in this portion of the storm. The rules of thumb for ship travel when a tropical cyclone is in their vicinity are to avoid them if at all possible and do not cross their forecast path (crossing the T).

neg: Cyclone at the surface as a westerly wind (toward the east). When the polar cyclone is weak, significant cold outbreaks occur. Under specific circumstances, upper level cold lows can break off from the base of the Tropical Upper Tropospheric Trough (TUTT), which is located mid-ocean in the Northern Hemisphere during the summer months. These upper tropospheric cyclonic vortices, also known as TUTT cells or TUTT lows, usually move slowly from east-northeast to west-southwest, and their bases generally do not extend below in altitude. A weak inverted surface trough within the trade wind is generally found underneath them, and they may also

neg: 2014–16 El Niño event ended in late May/early June. The 2014–16 El Niño event influenced tropical cyclone activity around the world, where it contributed to record breaking seasons in the Central Pacific and Australian tropical cyclone basins. By contrast, it limited Atlantic hurricane activity, producing strong vertical wind shear, increased atmospheric stability, stronger sinking motion and drier air across the tropical Atlantic. The Central Pacific basin saw its most active tropical cyclone season on record with 16 tropical cyclones recorded during 2015. Within the Southern Hemisphere, the El Niño pushed tropical cyclone activity in the South Pacific Ocean eastwards, with activity flourishing near Vanuatu,

neg: 2004 North Indian Ocean cyclone season 26, and despite being located unusually close to the equator, the system maintained convection about its circulation, aided by low wind shear. While the system was organizing, the center crossed the equator to reach about 0.5° S, thus becoming an anticyclonic circulation in the southern hemisphere. This was unusual, as the Coriolis effect is nonexistent along the equator—the Coriolis effect refers to planetary vorticity, which provides the spin in a cyclone. On November 28, the JTWC classified it as Tropical Cyclone 05A just 78 km (48 mi) from the equator. The IMD classified it as a depression the next day

neg: Cyclone Funso provided favorable conditions for development, including weak wind shear and good outflow. The system encountered warm sea surface temperatures, and favorable inflow from the south of its circulation was expected to increase after Subtropical Depression Dando dissipated over southern Africa. Late on January 18, the Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert, indicating a high chance of the system becoming a tropical cyclone. At 0000 UTC the next day, Météo-France (MF) classified it as Tropical Disturbance 8 about halfway between Mozambique and Madagascar in the northern Mozambique Channel. About six hours later, the agency upgraded the

neg: Westerly wind burst events commonly taking place when temperatures were present. The wind bursts also traveled along with the warm pool, propagating west to east. A westerly wind burst event can often result in the formation of twin tropical cyclones in the Pacific, with events occurring once per year on average. These events spur counter-clockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere—a key component of low pressure systems. For example, during July 2015 Typhoon Chan-hom and Tropical Cyclone Raquel developed simultaneously over the Northwestern and Southwestern Pacific, respectively, in conjunction with a westerly wind burst. This was also

neg: Tropical cyclone scales Indian Ocean, and are based on the systems estimated 3-minute maximum sustained winds. Tropical cyclones that develop in the Southern Hemisphere are only officially classified by the warning centres on one of two scales, which are both based on 10-minute sustained wind speeds: The Australian tropical cyclone intensity scale is used to classify systems within the Australian or South Pacific tropical cyclone basin. The scale used to classify systems in the South-West Indian Ocean is defined by Meteo France for use in various French territories, including New Caledonia and French Polynesia. The definition of sustained winds recommended by the World

neg: Radius of maximum wind of maximum wind. Because the strongest winds within a tropical cyclone lie at the RMW, this is the region of a tropical cyclone which generates the dominant waves near the storm, and ultimately ocean swell away from the cyclone. Tropical cyclones mix the ocean water within a radius three times that of the RMW, which lowers sea surface temperatures due to upwelling. Much is still unknown about the radius of maximum wind in tropical cyclones, including whether or not it can be predictable. Radius of maximum wind The radius of maximum wind (RMW) is the distance between the center of

neg: Tropical cyclone had one of the longest tracks observed within the Southern Hemisphere, traveling a distance of over during December 1993 and January 1994. While the number of storms in the Atlantic has increased since 1995, there is no obvious global trend; the annual number of tropical cyclones worldwide remains about 87 ± 10 (Between 77 and 97 tropical cyclones annually). However, the ability of climatologists to make long-term data analysis in certain basins is limited by the lack of reliable historical data in some basins, primarily in the Southern Hemisphere, while noting that a significant downward trend in tropical cyclone numbers

neg: Typhoon Chan-hom (2015) cyclone shortly thereafter. The remnants later caused flooding and power outages in the Russian Far East. During June 2015, a near record strength pulse in the Madden–Julian oscillation, lead to a period of significant weather across the Western Pacific. This significant weather included a major westerly wind burst during late June, which caused a set of twin tropical cyclones to develop. The first tropical cyclone developed in the Southern Hemisphere during June 28, before it later developed into Tropical Cyclone Raquel during June 30.The second tropical cyclone was first noted by the United States Joint Typhoon Warning Center (JTWC) as

neg: Cyclone Zoe wind shear, dry air and cooler sea surface temperatures. During December 31, as the system continued its southeastwards movement, it passed about to the southwest of Nadi, Fiji as a Category 2 tropical cyclone. By this time the system was transitioning into an extra tropical cyclone, while deep convection surrounding the system had significantly diminished. As a result of further weakening, the JTWC issued their final warning on Zoe during January 1, 2003, while the FMS reported that Zoe had weakened into a tropical depression. The system was subsequently recurved and started to move towards the southwest during January 2,

neg: Tropical cyclone scales to the Saffir–Simpson hurricane wind scale, however, regardless of intensity in this basin the JTWC labels all systems as tropical cyclones with TC numbers (plus any parenthesized names/placeholders, like typhoons and North Indian Ocean cyclones above). Tropical cyclones that occur within the Southern Hemisphere to the east of 90°E, are officially monitored by one or more tropical cyclone warning centres. These are run by the Fiji Meteorological Service, New Zealand's MetService, Indonesia's Badan Meteorologi, Klimatologi, dan Geofisika, Papua New Guinea's National Weather Service, while three others are run by the Australian Bureau of Meteorology. Within the region a tropical cyclone

neg: Tropical cyclone forecasting the worst possible scenario for a hurricane of a specific strength. The location of most tropical cyclone-related tornadoes is their northeast quadrant in the Northern Hemisphere and southeast quadrant in the Southern Hemisphere. Like most of the other forecasts for tropical cyclone effects, an accurate track forecast is required in order to produce an accurate tornado threat forecast. By looking at annual variations in various climate parameters, forecasters can make predictions about the overall number and intensity of tropical cyclones that will occur in a given season. For example, when constructing its seasonal outlooks, the Climate Prediction Center in the

neg: Pre-1970 Southern Hemisphere tropical cyclone seasons broke through the foreshore wall flooding the town. Onslow recorded a gust of 202 km/h and 283 mm of rain. On 1 April 1958, a small but intense cyclone hit the town of Bowen in north Queensland. Wind gusts of 98 knots (182 km/h) were recorded before the anemometer was blown away. A storm surge of 2 metres caused some destruction of beachside buildings, including the Hotel Ozone. A scrap of newsreel film about the 1958 cyclone that flattened Bowen is stored in ScreenSound, Australia's film and sound archive in Canberra. Among other damage to the town, the local cinema's

neg: 1990–91 South Pacific cyclone season within the southern Pacific. The JTWC issued warnings between 160°E and the International Date Line whilst the NWOC issued warnings for tropical cyclones forming between the International Date Line and the coasts of the Americas. Both the JTWC and the NWOC designated tropical cyclones with a number and a P suffix with numbers assigned in order to tropical cyclones developing within the whole of the Southern Hemisphere. TCWC Nadi, TCWC Wellington and TCWC Brisbane all use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a ten-minute period, while the JTWC estimates sustained winds over a one-minute period,

neg: Tropical cyclone the life of a tropical system. The deep layer mean flow, or average wind through the depth of the troposphere, is considered the best tool in determining track direction and speed. If storms are significantly sheared, use of wind speed measurements at a lower altitude, such as at the 70 kPa pressure surface ( above sea level) will produce better predictions. Tropical forecasters also consider smoothing out short-term wobbles of the storm as it allows them to determine a more accurate long-term trajectory. High-speed computers and sophisticated simulation software allow forecasters to produce computer models that predict tropical cyclone tracks

neg: Mediterranean tropical-like cyclone SSTs are needed. While significant deviations in air temperature have been noted around the time of Mediterranean tropical cyclones' formation, few anomalies in sea surface temperature coincide with their development, indicating that the formation of Medicanes is primarily controlled by higher air temperatures, not by anomalous SSTs. Similar to tropical cyclones, minimal wind shear—difference in wind speed and direction over a region—as well as abundant moisture and vorticity encourages the genesis of tropical cyclone-like systems in the Mediterranean Sea. Due to the confined character of the Mediterranean and the limited capability of heat fluxes—in the case of Medicanes, air—sea heat

neg: Tropical cyclone rainfall climatology to landslides, which still cause significant loss of life such as seen during Hurricane Mitch in Central America. Globally, tropical cyclone rainfall is more common across the northern hemisphere than across the southern hemisphere. This is mainly due to the normal annual tropical cyclone distribution, as between half and two-thirds of all tropical cyclones form north of the equator. Rainfall is concentrated near the 15th parallel in both hemispheres, with a less steep dropoff seen with latitude across the northern hemisphere, due to the stronger warm water currents seen in that hemisphere which allow tropical cyclones to remain tropical in

neg: South Atlantic tropical cyclone South Atlantic tropical cyclone 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. South Atlantic storms have developed year-round, with activity peaking during the months from November through May in this basin. Since 2011, the Brazilian Navy Hydrographic Center has started to assign names to tropical and subtropical systems

neg: 2002–03 South Pacific cyclone season cyclone in the Southern Hemisphere in recorded history, severely affecting areas of the Solomon Islands and Vanuatu. Cyclone Zoe developed from the South Pacific Convergence Zone (SPCZ) on January 23, east of Tuvalu. Initially developing slowly as a tropical depression, the predecessor to Zoe moved toward the west-southwest under the influence of a high pressure area. However, the storm entered an area of very favorable cyclone conditions. After reaching cyclone strength on December 25, rapid intensification ensued. By the next day, Zoe had already strengthened to a severe tropical cyclone. On December 27, Zoe attained wind speeds equivalent to Category

neg: Cyclone Winston Cyclone Winston Severe Tropical Cyclone Winston was the most intense tropical cyclone in the Southern Hemisphere on record, as well as the strongest to make landfall in the Southern Hemisphere, with the possible exception of 1899's Cyclone Mahina in both regards. Winston is also the costliest tropical cyclone on record in the South Pacific basin. The system was first noted as a tropical disturbance on 7 February 2016, when it was located to the northwest of Port Vila, Vanuatu. Over the next few days, the system gradually developed as it moved southeast, acquiring gale-force winds by 11 February. The following

neg: Inflow (meteorology) the underlying ocean surface is critical for tropical cyclone strengthening. A significant amount of the inflow in the cyclone is in the lowest of the atmosphere. Polar front theory is attributed to Jacob Bjerknes, and was derived from a coastal network of observation sites in Norway during World War I. This theory proposed that the main inflow into a cyclone was concentrated along two lines of convergence, one ahead (or east) of the low and another trailing equatorward (south in the Northern Hemisphere and north in the Southern Hemisphere) and behind (or west) of the low. The convergence line ahead

neg: Ekman transport the results will be relative to a north-south wind (although these solutions could be produced relative to wind in any other direction): where By solving this at "z"=0, the surface current is found to be (as expected) 45 degrees to the right (left) of the wind in the Northern (Southern) Hemisphere. This also gives the expected shape of the Ekman spiral, both in magnitude and direction. Integrating these equations over the Ekman layer shows that the net Ekman transport term is 90 degrees to the right (left) of the wind in the Northern (Southern) Hemisphere. Ekman transport Ekman transport, part

neg: Tropical cyclone forecasting United States considers the effects of the El Niño-Southern Oscillation, 25–40 year tropical cycle, wind shear over the oceans, and ocean surface temperature. Tropical cyclone forecasting Tropical cyclone forecasting is the science of forecasting where a tropical cyclone's center, and its effects, are expected to be at some point in the future. There are several elements to tropical cyclone forecasting: track forecasting, intensity forecasting, rainfall forecasting, storm surge, tornado, and seasonal forecasting. While skill is increasing in regard to track forecasting, intensity forecasting skill remains nearly unchanged over the past several years. Seasonal forecasting began in the 1980s in the

neg: Upwelling net of 90 degrees from the direction of the wind due to Coriolis forces and Ekman transport. Ekman transport causes the surface layer of water to move at about a 45 degree angle from the direction of the wind, and the friction between that layer and the layer beneath it causes the successive layers to move in the same direction. This results in a spiral of water movement down the water column. Then, it is the Coriolis forces that dictate which way the water will move; in the Northern hemisphere, the water is transported to the right of the direction

neg: Tropical cyclone tracking chart Tropical cyclone tracking chart A tropical cyclone tracking chart is used by those within hurricane-threatened areas to track tropical cyclones worldwide. In the north Atlantic basin, they are known as hurricane tracking charts. New tropical cyclone information is available at least every six hours in the Northern Hemisphere and at least every twelve hours in the Southern Hemisphere. Charts include maps of the areas where tropical cyclones form and track within the various basins, include name lists for the year, basin-specific tropical cyclone definitions, rules of thumb for hurricane preparedness, emergency contact information, and numbers for figuring out where tropical

neg: Pre-1970 Southern Hemisphere tropical cyclone seasons the eastern Gulf of Carpentaria, followed by heavy rains and wind damage over large areas of southern Queensland. On 2 April 1966 Shirley passed crossed the coast at King Bay where a ship recorded winds to 204 km/h. In Roebourne, Western Australia, winds destroyed some buildings. Sherlock station recorded 404 mm and subsequent floodwaters damaged the Mount Goldsworthy and Hamersley iron-ore railways under construction, roads and other facilities along the Pilbara coast. However, considering the intensity, the cyclone caused only minor damage. This storm merged with a non-tropical storm and led to the sinking of the TEV Wahine. Pre-1970 Southern

neg: Mount Washington (New Hampshire) westerly winds. Low-pressure areas are more favorable to develop along the coastline in the winter due to the relative temperature differences between the Northeastern United States and the Atlantic Ocean. With these factors combined, hurricane-force wind gusts are observed from the summit of the mountain on average of 110 days per year. Mount Washington once held the world record and still holds the Northern Hemisphere and Western Hemisphere record for directly measured surface wind speed, at , recorded on the afternoon of April 12, 1934. A new wind speed record was discovered in 2009: on April 10, 1996, Tropical Cyclone

neg: Typhoon Chan-hom (2015) Typhoon Chan-hom (2015) Typhoon Chan-hom, known in the Philippines as Typhoon Falcon, was a large, powerful and long-lived tropical cyclone that affected most countries in the western Pacific basin. The ninth named storm of the 2015 Pacific typhoon season, Chan-hom developed on June 29 from a westerly wind burst that also spawned Tropical Cyclone Raquel in the southern hemisphere. Chan-hom slowly developed while moving to the northwest, aided by warm waters but disrupted by wind shear. The storm meandered near the Northern Marianas Islands, passing over the island of Rota before beginning a steady northwest track. While near the island,

neg: Coriolis force flow. On a non-rotating planet, fluid would flow along the straightest possible line, quickly eliminating pressure gradients. Note that the geostrophic balance is thus very different from the case of "inertial motions" (see below), which explains why mid-latitude cyclones are larger by an order of magnitude than inertial circle flow would be. This pattern of deflection, and the direction of movement, is called Buys-Ballot's law. In the atmosphere, the pattern of flow is called a cyclone. In the Northern Hemisphere the direction of movement around a low-pressure area is anticlockwise. In the Southern Hemisphere, the direction of movement is clockwise

neg: Ekman spiral to the left in the Southern Hemisphere). Thus, when a persistent wind blows over an extended area of the ocean surface in the northern hemisphere, it causes a surface current which accelerates in that direction, which then experiences a Coriolis force and acceleration to the right of the wind: the current will turn gradually to the right as it gains speed. As the flow is now somewhat right of the wind, the Coriolis force perpendicular to the flow's motion is now partly directed "against" the wind. Eventually, the current will reach a top speed when the force of the wind,

neg: Cyclone Agni southern hemisphere. This was unusual, as the Coriolis effect is nonexistent along the equator—the Coriolis effect refers to planetary vorticity, which provides the spin in a cyclone. The JTWC later assessed the system as remaining in the northern hemisphere, reaching as far south as 0.7° N, or about 80 km (50 mi) from the equator. After the circulation organized further beneath the convection, the JTWC issued another TCFA at 0300 UTC on November 28. Three hours later, the agency classified the system as Tropical Cyclone 05A about 1300 km (800 mi) southwest of the southern tip of India. In a

neg: 2014–16 El Niño event wind speed and devastated Vanuatu; Cyclone Winston, was the most intense tropical cyclone in the Southern Hemisphere and devastated Fiji; Cyclone Fantala, which was the strongest storm in terms of 1-minute and 10-minute sustained winds in the South Indian Ocean; and Hurricane Patricia, which was the second-most-intense tropical cyclone on record globally in terms of barometric pressure, and the strongest in terms of 1-minute sustained winds. The El Niño event affected millions of people around the world, including in Africa, Central America, Southeast Asia, and the Pacific Islands. These effects included below or above-average rainfall, flooding, increased food insecurity, higher

neg: Cyclone Ron according to JTWC's annual report, Ron's lowest pressure was 892 hPa (26.3 inHg), what would make this cyclone, not only the third strongest cyclone in the South Pacific, but the third strongest cyclone ever recorded in the Southern Hemisphere, only behind Winston and Zoe. But these measures are unofficial. Cyclone Ron Severe Tropical Cyclone Ron was one of the most intense tropical cyclones on record in the South Pacific. The system was first noted as a tropical depression, to the northeast of Samoa on January 1, 1998. Over the next day the system gradually developed further and was named Ron

neg: 2012–13 Australian region cyclone season area of warmer sea surface temperatures and high windshear. At 10:25am EST, the TCWC Brisbane named the storm Tropical Cyclone Tim, as it intensified into a Category 1 storm with 10 minute wind speeds of . Located approximately north-east of Cairns, Tropical Cyclone Tim began to move in an east south-easterly direction towards Willis Island. It passed directly over the island, where the automated weather station recorded 10 minute wind gusts of before the station stopped recording. By late on the 14 of March, Tim rapidly intensified into a Category 2 storm on the Australian Scale, with maximum 10 minute

neg: Physical oceanography and 90 degrees to the left of the wind in the Southern Hemisphere. As the wind blows across the surface of the ocean, it "grabs" onto a thin layer of the surface water. In turn, that thin sheet of water transfers motion energy to the thin layer of water under it, and so on. However, because of the Coriolis Effect, the direction of travel of the layers of water slowly move farther and farther to the right as they get deeper in the Northern Hemisphere, and to the left in the Southern Hemisphere. In most cases, the very bottom layer

neg: Tropical cyclone windspeed climatology right front quadrant of the tropical cyclone. Severe damage is usually the result when the eyewall of a hurricane, typhoon or cyclone passes over land. The right front quadrant is also an area of a tropical cyclone were the winds are strongest. The reason that the winds are at the front right side of a storm in the northern hemisphere (and the front left hand side in the Southern Hemisphere) is because of the motion of a tropical cyclone contributing to its rotation. A 100 mph hurricane while stationary, might have winds of 100 mph on its right side in

neg: Tropical cyclone tracking chart apps, one can easily track the current activity of the Hurricanes. Red Cross has also launched several applications for this purpose. Tropical cyclone tracking chart A tropical cyclone tracking chart is used by those within hurricane-threatened areas to track tropical cyclones worldwide. In the north Atlantic basin, they are known as hurricane tracking charts. New tropical cyclone information is available at least every six hours in the Northern Hemisphere and at least every twelve hours in the Southern Hemisphere. Charts include maps of the areas where tropical cyclones form and track within the various basins, include name lists for the

neg: Pre-1970 Southern Hemisphere tropical cyclone seasons barometric pressure of 960 hPa and a maximum wind gust of 160 km/h. 635mm of rain fell in a 24 hour period at Yeppoon. In January, this tropical cyclone tracked from the Gulf of Carpentaria to Sydney. Three horseman were drowned on the 18th when Washpool Creek (80 km from Grafton) rose rapidly. Another four lives were lost in NSW from the cyclone including a girl swept off the Esplanade at Cronulla by the storm surge and waves, a boy electrocuted by fallen power lines at Gordon in Sydney, a man drowned near Goulburn and another man drowned in the

neg: Tropical cyclone track forecasting approaches from the cyclone's direction. Within 24 hours of the closest approach to the center, low clouds begin to move in, also known as the bar of a tropical cyclone, as the barometric pressure begins to fall more rapidly and the winds begin to increase. Within 18 hours of the center's approach, squally weather is common, with sudden increases in wind accompanied by rain showers or thunderstorms. Winds increase within 12 hours of the center's approach, occasionally reaching hurricane force. The ocean's surface becomes whipped with foam. Small items begin flying in the wind. Within 6 hours of the center's

neg: Tropical cyclogenesis strengthen. Strong wind shear can "blow" the tropical cyclone apart, as it displaces the mid-level warm core from the surface circulation and dries out the mid-levels of the troposphere, halting development. In smaller systems, the development of a significant mesoscale convective complex in a sheared environment can send out a large enough outflow boundary to destroy the surface cyclone. Moderate wind shear can lead to the initial development of the convective complex and surface low similar to the mid-latitudes, but it must relax to allow tropical cyclogenesis to continue. Limited vertical wind shear can be positive for tropical cyclone formation.

neg: Hazard mitigation in the Outer Banks for damaging the natural flow and movement of the Barrier Islands. There are several bridges along highway NC 12 which include the Wright Memorial Bridge, the Virginia Dare Memorial Bridge, the Washington Baum Bridge, and the Bonner Bridge. The Outer Banks are susceptible to reoccurring hurricanes that pummel their fragile coastline. Hurricanes are intense tropical cyclones that develop in the Atlantic Basin. A tropical cyclone is a non-frontal low-pressure system that forms over tropical or sub-tropical waters with organized thunderstorm activity and established surface wind circulation. A tropical cyclone begins as a tropical wave that commonly forms of the west

neg: Cyclone Cook Cyclone Cook Severe Tropical Cyclone Cook was the second named tropical cyclone of the 2016-17 South Pacific cyclone season. During April 5, 2017, the Fiji Meteorological Service started to monitor Tropical Disturbance 20F that had developed about to the northwest of the Fijian dependency of Rotuma. The system lied within an area of favourable conditions for further development with low to moderate vertical wind shear and warm sea surface temperatures of about . Over the next couple of days, the system moved south-westwards and gradually developed further, before it was classified as a tropical depression by the FMS during April

neg: Tropical cyclone track forecasting point, were not available at all over sea surfaces. About four days in advance of a typical tropical cyclone, an ocean of in height will roll in about every 10 seconds, moving towards the coast from the direction of the tropical cyclone's location. The ocean swell will slowly increase in height and frequency the closer a tropical cyclone gets to land. Two days in advance of the center's passage, winds go calm as the tropical cyclone interrupts the environmental wind flow. Within 36 hours of the center passage, the pressure begins to fall and a veil of white cirrus clouds

neg: Cyclone Nadia moving westward, its movement influenced by a subtropical ridge to the south. On March 17, the JTWC also began tracking the system. Due to cool, dry air, the system initially did not intensify, although its passage over warmer sea surface temperatures on March 19 allowed for strengthening. On March 19, MF classified the disturbance as Tropical Storm Nadia after rainbands developed. A day later, the JTWC designated Nadia as Tropical Cyclone 23S. After becoming a tropical storm, Nadia quickly intensified, developing a central dense overcast and later an eye. With minimal wind shear, the storm strengthened into a tropical cyclone

neg: Tropical cyclone tracking chart to depict. New tropical cyclone information is available at least every twelve hours in the Southern Hemisphere and at least every six hours in the Northern Hemisphere from Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers. In decades past, newspaper, television, and radio (including weather radio) were primary sources for this information. Local television stations within threatened markets would advertise tropical cyclone positions within the morning, evening, and nightly news during their weather segments. The Weather Channel includes the information within their tropical updates every hour during the Atlantic and Pacific hurricane seasons. Starting in the mid 1990s, the

neg: Cyclone Mahina from post-storm analysis. This would officially make Mahina the most intense cyclone recorded to have hit the Australian mainland, and the most intense tropical cyclone ever recorded in the Southern Hemisphere, a title currently held by Cyclone Winston. Cyclone Mahina also produced the largest storm surge on record, generating a 13-metre (43 foot)-high surge. Tropical Cyclone Mahina struck Australia on 4 March 1899, with a likely minimum central pressure of . Mahina ranks among the most intense cyclones ever observed in the Southern Hemisphere and almost certainly as the most intense cyclone ever observed off the Eastern states of Australia

neg: Cyclone by convection as are tropical cyclones, nor the cold and warm air mass interactions as are extratropical cyclones, but is an artifact of the global air movement of the Polar cell. The base of the polar low is in the mid to upper troposphere. In the Northern Hemisphere, the polar cyclone has two centers on average. One center lies near Baffin Island and the other over northeast Siberia. In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude. When the polar vortex is strong, its effect can be felt

neg: Cyclone Hollanda did not strike the island of Réunion, Hollanda produced strong wind gusts that peaked at in Sainte-Rose. Rainfall on the island peaked at at Grand Coude. The cyclone left damage to crops, power systems, telephones, and the water network, mostly due to the strong winds. Cyclone Hollanda Cyclone Hollanda was the worst tropical cyclone in Mauritius in 19 years. It formed on February 6, 1994, in the central Indian Ocean in the southern hemisphere. The cyclone moved southwestward for much of its duration, striking Mauritius on February 10 at peak intensity with winds of 218 km/h (135 mph). It later

neg: Cyclone Pam pressure, after Winston of 2016 and Zoe of 2002. In addition, Pam is tied with Orson, Monica and Fantala for having the second strongest ten-minute maximum sustained winds of any cyclone in the Southern Hemisphere. Thousands of homes, schools and buildings were damaged or destroyed, with an estimated 3,300 people displaced as a result. Pam formed on 6 March, east of the Solomon Islands and tracked slowly in a generally southward direction, slowly intensifying as it did so. Two days later, the disturbance reached tropical cyclone intensity and, over subsequent days, Pam gradually strengthened before reaching Category 5 cyclone status

neg: Cyclone Anne Meteorological Service started to monitor a shallow tropical depression that developed within the monsoon trough about northeast of Tuvalu. At around the same time, a twin depression developed within the Northern Hemisphere monsoon trough, which eventually became Typhoon Roy. Over the next two days the Southern Hemisphere system developed further as it was steered towards the south-southwest along an area of high pressure, before it became equivalent to a tropical storm while passing through the Tuvaluan islands. As a result, the United States Joint Typhoon Warning Center designated the system as Tropical Cyclone 07P and started to issue advisories on

neg: Q-Vectors forces ascend and divergent formula_30 forces descend. Q-vectors and all ageostrophic flow exist to preserve thermal wind balance. Therefore, low level Q-vectors tend to point in the direction of low-level ageostrophic winds. Q-vectors can be determined wholly with: geopotential height (formula_32) and temperature on a constant pressure surface. Q-vectors always point in the direction of ascending air. For an idealized cyclone and anticyclone in the Northern Hemisphere (where formula_33), cyclones have Q-vectors which point parallel to the thermal wind and anticyclones have Q-vectors that point antiparallel to the thermal wind. This means upward motion in the area of warm air

neg: Trade winds both hemispheres by the Coriolis effect. These winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere. Because winds are named for the direction from which the wind is blowing, these winds are called the northeasterly trade winds in the Northern Hemisphere and the southeasterly trade winds in the Southern Hemisphere. The trade winds of both hemispheres meet at the doldrums. As they blow across tropical regions, air masses heat up over lower latitudes due to more direct sunlight. Those that develop over land (continental) are drier and hotter than those that

neg: Cyclone Cook high tide. As a result, the French education ministry cancelled some nationwide exams, while tourists were evacuated from seaside bungalows. Cyclone Cook Severe Tropical Cyclone Cook was the second named tropical cyclone of the 2016-17 South Pacific cyclone season. During April 5, 2017, the Fiji Meteorological Service started to monitor Tropical Disturbance 20F that had developed about to the northwest of the Fijian dependency of Rotuma. The system lied within an area of favourable conditions for further development with low to moderate vertical wind shear and warm sea surface temperatures of about . Over the next couple of days, the

neg: Cyclone (the mesoscale of meteorology), within a convective storm. Air rises and rotates around a vertical axis, usually in the same direction as low-pressure systems in both northern and southern hemisphere. They are most often cyclonic, that is, associated with a localized low-pressure region within a supercell. Such storms can feature strong surface winds and severe hail. Mesocyclones often occur together with updrafts in supercells, where tornadoes may form. About 1,700 mesocyclones form annually across the United States, but only half produce tornadoes. A tornado is a violently rotating column of air that is in contact with both the surface of

neg: 1980 Pacific hurricane season northern hemisphere tropical cyclone to cross the dateline from west to east since Tropical Storm Virginia in 1968. Agatha originated from a tropical depression that formed south-southwest of Acapulco on June 9. After becoming better organized, EPHC upgraded the depression into a tropical storm later that day, giving it the name Agatha. The storm turned north then northwest and strengthened into a hurricane. On June 12, Agatha reached its peak intensity with maximum sustained winds of 115 mph (185 km/h), a category 3 hurricane on the Saffir–Simpson hurricane wind scale. After entering an area with cooler sea surface temperature and

neg: Tropical Atlantic SST Dipole of surface ocean currents in transporting warm waters and heat meridionally, since surface wind-induced Ekman puming appears to be the key contributor for such THC and heat content anomalies. The meridional (interhemispheric) mode demonstrates seasonal changes, arriving to a maximum during the boreal spring, on and north of the equator. The seasonal changes in surface wind forcing, which are closely linked to the seasonal displacement of the ITCZ, incite a response on the ocean surface, affecting current systems in the tropical Atlantic as well as the slope of the underlying thermocline (THC). For example, during the Southern hemisphere spring and

neg: Tropical cyclone rainfall climatology of the precipitation falling to the left and downwind of the shear vector, or downshear left. In other words, southwesterly shear forces the bulk of the rainfall north-northeast of the center. If the wind shear is strong enough, the bulk of the rainfall will move away from the center leading to what is known as an exposed circulation center. When this occurs, the potential magnitude of rainfall with the tropical cyclone will be significantly reduced. As a tropical cyclone interacts with an upper-level trough and the related surface front, a distinct northern area of precipitation is seen along the front

neg: Tropical cyclone every twelve hours in the Southern Hemisphere and at least every six hours in the Northern Hemisphere from Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers. Tropical cyclones are classified into three main groups, based on intensity: tropical depressions, tropical storms, and a third group of more intense storms, whose name depends on the region. For example, if a tropical storm in the Northwestern Pacific reaches hurricane-strength winds on the Beaufort scale, it is referred to as a "typhoon"; if a tropical storm passes the same benchmark in the Northeast Pacific Basin, or in the North Atlantic, it is

neg: Tropical cyclone rainfall forecasting become highly asymmetric, with most of the precipitation falling to the left and downwind of the shear vector, or downshear left. In other words, southwesterly shear forces the bulk of the rainfall north-northeast of the center. If the wind shear is strong enough, the bulk of the rainfall will move away from the center leading to what is known as an exposed circulation center. When this occurs, the potential magnitude of rainfall with the tropical cyclone will be significantly reduced. As a tropical cyclone interacts with an upper-level trough and the related surface front, a distinct northern area of precipitation

neg: Outflow (meteorology) of a line of storms. Often, the outflow boundary will bow in the direction it is moving the quickest. The development of a significant mesoscale convective complex can send out a large enough outflow boundary to weaken the cyclone as the tropical cyclone center moves into the more stable air mass behind the leading edge of thunderstorm outflow, or outflow boundary. Moderate vertical wind shear can lead to the initial development of the convective complex and surface low similar to the mid-latitudes, but it must relax to allow tropical cyclogenesis to continue. While the most obvious motion of clouds is

neg: 2017–18 South Pacific cyclone season had developed about to the southwest of Rennell and Bellona Province of the Solomon Islands. The system was poorly organised with deep atmospheric convection, displaced to the east of the system's consolidating low-level circulation center. The disturbance was subsequently classified as Tropical Low 21U by the BoM during March 12, as it moved southwards within an area of low vertical wind shear and warm sea surface temperatures. Despite not making landfall, Tropical Cyclone Josie caused heavy rainfall and sustained gale-force winds in southern Fiji. Severe flooding occurred in the city of Nadi, and at least five people were washed away

neg: Tropical cyclone warnings and watches forecasting their track remains an uncertain science. New tropical cyclone position and forecast information is available at least every twelve hours in the Southern Hemisphere and at least every six hours in the Northern Hemisphere from Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers. In conjunction with the National Hurricane Center, the national meteorological and hydrological services of Central America, the northern Atlantic Ocean, and the northeastern Pacific Ocean east of the 140th meridian west, excluding mainland Africa and Europe, all issue tropical storm/hurricane watches and warnings. Tropical storm watches are issued when gale and storm force winds of

neg: Thermal wind where the temperature is greatest. Differentiating the geostrophic wind, formula_6 (where formula_7 is the Coriolis parameter, formula_8 is the vertical unit vector, and the subscript "p" on the gradient operator denotes gradient on a constant pressure surface) with respect to pressure, and integrate from pressure level formula_9 to formula_10, we obtain the thermal wind equation: formula_11. Substituting the hypsometric equation, one gets a form based on temperature, formula_12. Note that thermal wind is at right angles to the horizontal temperature gradient, counter clockwise in the northern hemisphere. In the southern hemisphere, the change in sign of formula_13 flips the direction.

neg: High-pressure area Hadley cells help form the subtropical ridge, steer tropical waves and tropical cyclones across the ocean and is strongest during the summer. The subtropical ridge also helps form most of the world's deserts. On English-language weather maps, high-pressure centers are identified by the letter H. Weather maps in other languages may use different letters or symbols. The direction of wind flow around an atmospheric high-pressure area and a low-pressure area, as seen from above, depends on the hemisphere. High-pressure systems rotate clockwise in the northern Hemisphere; low-pressure systems rotate clockwise in the southern hemisphere. The scientific terms in English used

neg: 1995 North Indian Ocean cyclone season An area of convection blossomed near northern Sumatra on November 18, associated with the monsoon. Aided by the same westerly wind burst that assisted Cyclone Daryl in the southern hemisphere, the disturbance gradually organized and persisted while moving west-northwestward through the Bay of Bengal. Late on November 21, the system developed into a depression, which the JTWC classified as Tropical Cyclone 04B. Steady intensification ensued; by November 23, the JTWC upgraded the cyclone to the equivalent of a minimal hurricane, and the IMD steadily upgraded the storm to increasing categories. The storm turned to the north and northeast around a

neg: Ekman transport Ekman transport Ekman transport, part of Ekman motion theory first investigated in 1902 by Vagn Walfrid Ekman, refers to the wind-driven net transport of the surface layer of a fluid that, due to the Coriolis effect, occurs at 90° to the direction of the surface wind. This phenomenon was first noted by Fridtjof Nansen, who recorded that ice transport appeared to occur at an angle to the wind direction during his Arctic expedition during the 1890s. The direction of transport is dependent on the hemisphere: in the northern hemisphere, transport occurs at 90° clockwise from wind direction, while in the

neg: 1991–92 South-West Indian Ocean cyclone season task force, also issued tropical cyclone warnings for the southwestern Indian Ocean. During the season, there was an El Niño event that caused tropical cyclogenesis in the southern hemisphere to shift more to the east. In addition, the monsoon trough, which helped spawn most of the storms in the season, was weaker than normal in the Indian Ocean. The number of tropical depressions forming was above average, although there were fewer days than normal with tropical cyclone activity. On December 17, the JTWC began monitoring a tropical depression about 700 km (440 mi) west of Diego Garcia in association with

neg: 2002–03 Australian region cyclone season 2002–03 Australian region cyclone season The 2002–03 Australian region cyclone season included Cyclone Inigo, which tied with Cyclone Gwenda in 1999 as the most intense tropical cyclone on record in the Australian basin. It began on 1 November 2002 and ended on 30 April 2003. The regional tropical cyclone operational plan also defines a "tropical cyclone year" separately from a "tropical cyclone season", which runs from 1 July 2002 to 30 June 2003. These dates conventionally delimit the period of each year when most tropical cyclones form in the Australian region, which is defined as in the southern hemisphere between

neg: Extratropical cyclone off the western coast of Canada. The Braer Storm of January 1993 was the strongest extratropical cyclone known to occur across the northern Atlantic Ocean, with a central pressure of . In 2012, Hurricane Sandy transitioned to a post-tropical cyclone on the night of October 29; a few minutes later it made landfall on the New Jersey coast as an extratropical storm with winds similar to a Category 1 hurricane and a wind field of over . In the Southern Hemisphere, a violent extratropical storm hit Uruguay on August 23–24, 2005, killing 10 people. The system's winds exceeded 100 mph

neg: Tropical cyclone a theoretical upper bound on the strongest wind speed that a tropical cyclone can attain. Because evaporation increases linearly with wind speed (just as climbing out of a pool feels much colder on a windy day), there is a positive feedback on energy input into the system known as the Wind-Induced Surface Heat Exchange (WISHE) feedback. This feedback is offset when frictional dissipation, which increases with the cube of the wind speed, becomes sufficiently large. This upper bound is called the "maximum potential intensity", formula_7, and is given by where formula_9 is the temperature of the sea surface, formula_10 is