A tropical cyclone rainfall climatology is developed to determine rainfall characteristics of past tropical cyclones. A tropical cyclone rainfall climatology can be used to help forecast current or upcoming tropical cyclone impacts. The degree of a tropical cyclone rainfall impact depends upon speed of movement, storm size, and degree of vertical wind shear. One of the most significant threats from tropical cyclones A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic is heavy rainfall. Large, slow moving, and non-sheared tropical cyclones produce the heaviest rains. The intensity of a tropical cyclone appears to have little bearing on its potential for rainfall over land, but satellite measurements over the last several years show that more intense tropical cyclones produce noticeably more rainfall over water. Flooding from tropical cyclones remains a significant cause of fatalities, particularly in low-lying areas.
Anticipating a flood event
See also: Tropical cyclone rainfall forecasting Tropical cyclone rainfall forecasting involves using scientific models and other tools to predict the precipitation expected in tropical cyclones such as hurricanes and typhoons. Knowledge of tropical cyclone rainfall climatology is helpful in the determination of a tropical cyclone rainfall forecast. More rainfall falls in advance of the centerWhile inland flooding A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, is common to tropical cyclones, there are factors which lead to excessive rainfall from tropical cyclones. Slow motion, as was seen during Hurricane Danny (1997) Hurricane Danny was the only hurricane to make landfall in the United States during the 1997 Atlantic hurricane season, and the second hurricane and fourth tropical storm of the season. The system became the earliest 5th tropical or subtropical storm of the Atlantic season when it reached tropical storm strength on July 17, and held that record and Hurricane Wilma Hurricane Wilma was the most intense hurricane ever recorded in the Atlantic basin. Wilma was the twenty-second storm , thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane of the record-breaking 2005 season, can lead to high amounts of rainfall. The presence of mountains/hills near the coast, like across much of Mexico In Pre-Columbian Mesoamerica many cultures matured into advanced civilizations such as the Olmec, the Toltec, the Teotihuacan, the Zapotec, the Maya and the Aztec before the first contact with Europeans. In 1521, Spain conquered and colonized the territory, which was administered as the viceroyalty of New Spain which would eventually become Mexico, Haiti Haiti (pronounced /ˈheɪti/ ; French Haïti, pronounced: [a.iti]; Haitian Creole: Ayiti, Haitian Creole pronunciation: [ajiti]), officially the Republic of Haiti (République d'Haïti ; Repiblik Ayiti) is a Caribbean country. Along with the Dominican Republic, it occupies the island of Hispaniola, in the Greater Antillean archipelago. Ayiti (land, the Dominican Republic Inhabited by Taínos since the 7th century, the territory of the Dominican Republic was reached by Christopher Columbus in 1492 and became the site of the first permanent European settlement in the Americas, namely Santo Domingo, the country's capital and Spain's first capital in the New World. In Santo Domingo stand, among other firsts in the, Central America Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Central America is considered to be part of the Mesoamerican biodiversity hotspot, excluding the southern portions of Panama, Madagascar Madagascar, or Republic of Madagascar , is an island nation in the Indian Ocean off the southeastern coast of Africa. The main island, also called Madagascar, is the fourth-largest island in the world, Réunion Réunion (French: La Réunion, IPA: [la ʁeynjɔ̃] ; previously Île Bourbon) is a French island of about 800,000 population located in the Indian Ocean, east of Madagascar, about 200 kilometres (120 mi) south west of Mauritius, the nearest island. Since August 2010, the Pitons, Cirques and Remparts of the island, covering more than 40% of its, China China is seen variously as an ancient civilization extending over a large area in East Asia, a nation and/or a multinational entity, and Japan Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is acts to magnify rainfall potential due to forced upslope flow into the mountains. Strong upper level forcing from a trough moving through the Westerlies and its associated cold front The cooler, denser air wedges under the less dense warmer air, lifting it, which can cause the formation of a narrow line of showers and thunderstorms when enough moisture is present. This upward motion causes lowered pressure along the cold front. On weather maps, the surface position of the cold front is marked with the symbol of a blue line of, as was the case during Hurricane Floyd Hurricane Floyd was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd triggered the third largest evacuation in US history when 2.6 million coastal residents of five states were ordered from their homes as it approached. The Cape Verde-type hurricane formed off the coast of Africa and, can lead to high amounts even from systems moving at an average forward motion. Larger tropical cyclones drop more rainfall as they precipitate upon one spot for a longer time frame than average or small tropical cyclones. A combination of two of these factors could be especially crippling, as was seen during Hurricane Mitch Hurricane Mitch was the most powerful hurricane of the 1998 Atlantic hurricane season, with maximum sustained winds of 180 mph . The storm was the thirteenth tropical storm, ninth hurricane, and third major hurricane of the season. At the time, Hurricane Mitch was the strongest Atlantic hurricane observed in the month of October, though it has in Central America Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Central America is considered to be part of the Mesoamerican biodiversity hotspot, excluding the southern portions of Panama.[1] During the 2005 season, flooding related to slow-moving Hurricane Stan Hurricane Stan was the eighteenth named tropical storm and eleventh hurricane of the 2005 Atlantic hurricane season. It was also the sixth of seven tropical cyclones to make landfall in Mexico. Stan was a relatively weak storm that only briefly reached hurricane status. It was embedded in a larger non-tropical system of rainstorms that dropped's broad circulation led to 1,662–2,000 deaths.[2]
General distribution within a tropical cyclone
| Rainfall Rate per day within radius of the center (Riehl) | |||
|---|---|---|---|
| Radius (mi) | Radius (km) | Amount (in) | Amount (mm) |
| 35 | 56 | 33.98 | 863 |
| 70 | 112 | 13.27 | 337 |
| 140 | 224 | 4.25 | 108 |
| 280 | 448 | 1.18 | 30 |
Isaac Cline was the first to investigate rainfall Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface. On Earth, it is the condensation of atmospheric water vapor into drops of water heavy distribution around tropical cyclones in the early 1900s. He found that a larger proportion of rainfall falls in advance of the center (or eye) than after the center's passage, with the highest percentage falling in the right front quadrant. Father Viñes of Cuba The Republic of Cuba (pronounced /ˈkjuːbə/ ; Spanish: República de Cuba, pronounced [reˈpuβlika ðe ˈkuβa] ( listen)) is an island country in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos found that some tropical cyclones have their highest rainfall rates in the rear quadrant within a training (non-moving) inflow band.[3] Normally, as a tropical cyclone intensifies, its heavier rainfall rates become more concentrated around its center.[4] Rainfall is found to be heaviest in tropical cyclone's inner core, whether it be the eyewall The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather of a cyclone occurs. The cyclone's lowest barometric pressure occurs in the or central dense overcast, within a degree latitude of the center, with lesser amounts farther away from the center.[5] Most of the rainfall in tropical cyclones is concentrated within its radius of gale-force (34 knots/39 mph/63 km/h) winds.[6] Rainfall is more common near the center of tropical cyclones overnight. Over land, outer bands are more active during the heating of the day, which can act to restrict inflow into the center of the cyclone. Recent studies have shown that half of the rainfall within a tropical cyclone is stratiform in nature.[7] The chart to the right was developed by Riehl in 1954 using meteorological equations that assume a gale radius of about 140 miles (230 km), a fairly symmetric cyclone, and does not consider topographic effects or vertical wind shear. Local amounts can exceed this chart by a factor of two due to topography. Wind shear tends to lessen the amounts below what is shown on the table.
Relation to storm size
The relative sizes of Typhoon Tip Typhoon Tip was the largest and most intense tropical cyclone on record. The nineteenth tropical storm and twelfth typhoon of the 1979 Pacific typhoon season, Tip developed out of a disturbance in the monsoon trough on October 4 near Pohnpei. Initially, a tropical storm to its northwest hindered the development and motion of Tip, though after it, Cyclone Tracy Cyclone Tracy was a tropical cyclone that devastated the city of Darwin, Northern Territory, Australia, from Christmas Eve to Christmas Day, 1974. It is the most compact hurricane or equivalent-strength tropical cyclone on record in the Australian basin, with gale-force winds extending only 48 kilometres (30 mi) from the centre and was the most, and the United States.Larger tropical cyclones have larger rain shields, which can lead to higher rainfall amounts farther from the cyclone's center.[6] This is generally due to the longer time frame rainfall falls at any one spot in a larger system, when compared to a smaller system. Some of the difference seen concerning rainfall between larger and small storms could be the increased sampling of rainfall within a larger tropical cyclone when compared to that of a compact cyclone; in other words, the difference could be the result of a statistical problem.
Slow/looping motion on rainfall magnitude
Storms which have moved slowly, or loop, over a succession of days lead to the highest rainfall amounts for several countries. Riehl calculated that 33.97 inches (863 mm) of rainfall per day can be expected within one-half degree, or 35 miles (56 km), of the center of a mature tropical cyclone. Many tropical cyclones progress at a forward motion of 10 knots, which would limit the duration of this excessive rainfall to around one-quarter of a day, which would yield about 8.50 inches (216 mm) of rainfall. This would be true over water, within 100 miles (160 km) of the coastline,[8] and outside topographic features. As a cyclone moves farther inland and is cut off from its supply of warmth and moisture (the ocean), rainfall amounts from tropical cyclones and their remains decrease quickly.[9]
Vertical wind shear impact on rainfall shield
Vertical wind shear Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere. Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across fronts and near the coast, and vertical shear typically near the surface, forces the rainfall pattern around a tropical cyclone to 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.[10] 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.
Effect of interaction with frontal boundaries/upper level troughs
As a tropical cyclone A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic interacts with an upper-level trough A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts and the related surface front Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations. Weather maps are created by plotting or tracing the values of relevant quantities such as sea level pressure, temperature, and cloud cover onto a, a distinct northern area of precipitation is seen along the front ahead of the axis of the upper level trough. This type of interaction can lead to the appearance of the heaviest rainfall falling along and to the left of the tropical cyclone track, with the precipitation streaking hundreds of miles or kilometers downwind from the tropical cyclone.[11] The stronger the upper trough picking up the tropical cyclone, the more significant the left of track shift in the rainfall distribution tends to be.[7]
Mountains
Moist air forced up the slopes of coastal hills and mountain chains can lead to much heavier rainfall than in the coastal plain. This heavy rainfall can lead to landslides, which still cause significant loss of life such as seen during Hurricane Mitch Hurricane Mitch was the most powerful hurricane of the 1998 Atlantic hurricane season, with maximum sustained winds of 180 mph . The storm was the thirteenth tropical storm, ninth hurricane, and third major hurricane of the season. At the time, Hurricane Mitch was the strongest Atlantic hurricane observed in the month of October, though it has in Central America Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Central America is considered to be part of the Mesoamerican biodiversity hotspot, excluding the southern portions of Panama.
Global distribution
Global tropical cyclone rainfall in 2005Globally, 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 nature at higher latitudes than south of the equator. In the southern hemisphere, rainfall impacts will be most common between January and March, while north of the equator, tropical cyclone rainfall impacts are more common between June and November.[7] Japan Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is receives over half of its rainfall from typhoons.[12]
United States tropical cyclone rainfall statistics
U.S. Tropical Cyclone A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic Rainfall Accumulations per time frame See also: United States tropical cyclone rainfall climatologyBetween 1970-2004, inland flooding from tropical cyclones caused a majority of the fatalities in the United States ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language.[13] This statistic changed in 2005, when Hurricane Katrina Hurricane Katrina of the 2005 Atlantic hurricane season was the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall. At least 1,836 people lost their lives in the actual hurricane and in the subsequent floods, making's impact alone shifted the most deadly aspect of tropical cyclones back to storm surge Storm surge is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level. Low pressure at the center of a weather system also has a small secondary effect,, which has historically been the most deadly aspect of strong tropical cyclones.[14] On average, five tropical cyclones of at least tropical depression strength lead to rainfall across the contiguous United States annually, contributing around a quarter of the annual rainfall to the southeast United States. While many of these storms form in the Atlantic Basin, some systems or their remnants move through Mexico from the Eastern Pacific Basin. The average storm total rainfall for a tropical cyclone impacting the lower 48 from the Atlantic Basin is about 16 inches (406 mm), with 70–75 percent of the storm total falling within a 24-hour period. The highest point total was seen during Amelia 1978 Tropical Storm Amelia was a weak tropical storm that brought heavy rain and damage to Texas in July of the 1978 Atlantic hurricane season. Amelia formed on July 30 after wandering around the Atlantic Ocean and Caribbean Sea for a week and a half. Amelia affected the Texas coast for 2 days, making landfall in Corpus Christi and becoming, when 48 inches (1,218 mm) fell upon central Texas.[15]
See also
- China tropical cyclone rainfall climatology
- Extratropical cyclone Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and horizontal gradients in temperature and dew point
- List of wettest tropical cyclones by country This is a list of wettest tropical cyclones by country, using all known available sources. Data is most complete for Australia, Cuba, the Dominican Republic, Japan, Hong Kong, Mexico, Taiwan, Yap, Chuuk, and the United States, with fragmentary data available for other countries. The French region of Réunion holds several world records for
- Tropical cyclone A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic
- Tropical cyclone rainfall forecasting Tropical cyclone rainfall forecasting involves using scientific models and other tools to predict the precipitation expected in tropical cyclones such as hurricanes and typhoons. Knowledge of tropical cyclone rainfall climatology is helpful in the determination of a tropical cyclone rainfall forecast. More rainfall falls in advance of the center
- Tropical cyclogenesis Tropical cyclogenesis is the technical term describing the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to
- United States tropical cyclone rainfall climatology
References
Printed media
- Ivan Ray Tannehill. Hurricanes. Princeton University Press: Princeton, 1942.
- Herbert Riehl. Tropical Meteorology. McGraw-Hill Book Company, Inc.: New York, 1954.
- Terry Tucker. Beware the Hurricane! Hamilton Press: Bermuda, 1966.
|
915px x 1354px | 57.80kB
[source page]
^ David M Roth Tropical Storm Hermine 1980 Rainfall Graphic Retrieved on 2008 05 21
