Typhoon Zelda (1991)
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Typhoon Zelda (1991)
Severe Tropical Storm Zelda was the last tropical cyclone of the 1991 Pacific typhoon season; it struck the Marshall Islands on November 28. The area of low pressure that eventually became Zelda formed near the International Date Line, and strengthened into a tropical depression on November 27. The Joint Typhoon Warning Center (JTWC) reported that the depression had reached tropical storm intensity near the Marshall Islands on November 28, thus naming it Zelda. On November 29, the storm quickly strengthened to according to the JTWC, equivalent to a Category 1 typhoon on the Saffir–Simpson hurricane wind scale. It reached a peak of according to the JTWC, and according to the Japanese Meteorological Agency (JMA), with a barometric pressure of . Zelda weakened into a tropical storm on December 2, and then a tropical depression two days later. The JTWC discontinued warnings late on December 4, while the JMA declared the storm to be extratropical the ne ...
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Marshall Islands
The Marshall Islands, officially the Republic of the Marshall Islands, is an island country west of the International Date Line and north of the equator in the Micronesia region of the Northwestern Pacific Ocean. The territory consists of 29 coral atolls and five main islands as well as 1,220 other very small ones, divided across two Archipelago, island chains: Ratak in the east and Ralik in the west. 97.87% of its territory is water, the largest proportion of water to land of any sovereign state. The country shares Maritime boundary, maritime boundaries with Wake Island to the north, Kiribati to the southeast, Nauru to the south, and the Federated States of Micronesia to the west. The capital city, capital and largest city is Majuro, home to approximately half of the country's population. The Marshall Islands are one of only four atoll based nations in the entire world. Austronesian settlers reached the Marshall Islands as early as the 2nd millennium BC and introduced Southeas ...
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Federal Emergency Management Agency
The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive order (United States), Executive Orders on April 1, 1979. The agency's primary purpose is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and U.S. state, state authorities. The governor of the state in which the disaster occurs must declare a state of emergency and formally request from the President of the United States, president that FEMA and the Federal government of the United States, federal government respond to the disaster. The only exception to the state's gubernatorial declaration requirement occurs when an emergency or disaster takes place on federal property or to a federal asset—for example, the 1995 Oklahoma City bombing, bombing of the Alfred ...
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Infrared Photography
In infrared photography, the photographic film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700  nm to about 900 nm. Film is usually sensitive to visible light too, so an infrared-passing filter is used; this lets infrared (IR) light pass through to the camera, but blocks all or most of the visible light spectrum; these filters thus look black (opaque) or deep red. When these filters are used together with infrared-sensitive film or sensors, " in-camera effects" can be obtained; false-color or black-and-white images with a dreamlike or sometimes lurid appearance known as the "Wood Effect," an effect mainly caused by foliage (such as tree leaves and grass) strongly reflecting infrared in the same way visible light is reflected from snow. There is a small contribution from c ...
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Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclone, anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather satellite imagery or a fine line on weather radar imagery. For observers on the ground, a thunderstorm outflow boundary often approaches in otherwise clear skies as a low, thick cloud that brings with it a gust front. Low-level outflow boundaries can disrupt the center of small tropical cyclones. However, outflow aloft is essential for the strengthening of a tropical cyclone. If this outflow is restricted or undercut, the tropical cyclone weakens. If two tropical cyclones are close, the upper-level outflow from the upwind system can limit the development of the other system. Thunderstorms For thunderstorms, outflow tends to indicate the development of a system. Large quan ...
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Atlantic Oceanographic And Meteorological Laboratory
The Atlantic Oceanographic and Meteorological Laboratory (AOML), a federal research laboratory, is part of the National Oceanic and Atmospheric Administration's (NOAA) Office of Oceanic and Atmospheric Research (OAR), located in Miami in the United States. AOML's research spans tropical cyclone and hurricanes, coastal ecosystems, oceans and human health, climate studies, global carbon systems, and ocean observations. It is one of seven NOAA Research Laboratories (RLs). AOML’s organizational structure consists of an Office of the Director and three scientific research divisions. The Office of the Director oversees the Laboratory’s scientific programs, as well as its financial, administrative, computer, outreach/education, and facility management services. Research programs are augmented by Cooperative Institutes, such as the Cooperative Institute for Marine and Atmospheric Studies (CIMAS), a joint enterprise with the University of Miami’s Rosenstiel School of Marine, Atmos ...
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Maximum Sustained Winds
The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a certain distance from the center, known as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are determined via their sampling and averaging the sampled results over a period of time. Wind measuring has been standardized globally to reflect the winds at above mean sea level, and the maximum sustained wind represents the highest average wind over either a one-minute (US) or ten-minute time span (see the definition, below), anywhere within the tropical cyclone. Surface winds are highly variable due to friction between the atmosphere and the Earth's surface, as well as near hills and mountains over land. Over the ocean, satellite imagery is often used to estimate the maximum sustained winds within a tropical cyclone. Land, ship, aircraft reconnaissance observations, an ...
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Tropical Storm
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its location and strength, a tropical cyclone is called a hurricane (), typhoon (), tropical storm, cyclonic storm, tropical depression, or simply cyclone. A hurricane is a strong tropical cyclone that occurs in the Atlantic Ocean or northeastern Pacific Ocean. A typhoon is the same thing which occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones". In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of or more. Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean sur ...
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Regional Specialized Meteorological Center
A Regional Specialized Meteorological Centre (RSMC) is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as part of the World Weather Watch. Environmental emergency response programme As a result of the poor communications between countries following the Chernobyl disaster in the Spring of 1986, the World Meteorological Organization (WMO) was requested by the International Atomic Energy Agency (IAEA) and other international organizations to arrange for early warning messages about nuclear accidents to be transmitted over the Global Telecommunications System (GTS). In addition some WMO member countries that lacked extensive forecasting capability requested that specialized pollutant transport and dispersion forecasts be provided during these emergencies. As a result, during 1989 Meteo-France (MF), Environment Canada (EC) and the United Kingdom ...
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Japan Meteorological Agency
The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered in Minato, Tokyo the government agency, agency collects data on meteorology, hydrology, seismology, volcanology, and other related fields. The JMA is responsible for collecting and disseminating weather data and Forecasting, forecasts to the public, as well as providing specialized information for aviation and Marine weather forecasting, marine sectors. Additionally, the JMA issues warnings for volcanic eruptions and is integral to the nationwide Earthquake Early Warning (Japan), Earthquake Early Warning (EEW) system. As one of the Regional Specialized Meteorological Centers designated by the World Meteorological Organization (WMO), the JMA also Forecasting, forecasts, Tropical cyclone naming, names, and distributes warnings for tropical ...
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Tropical Cyclone Formation Alert
A Tropical Cyclone Formation Alert (TCFA) is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Fleet Weather Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming from a tropical disturbance that has been monitored. Such alerts are generally always issued when it is fairly certain that a tropical cyclone will form and are not always released before cyclogenesis, particularly if the cyclone appears suddenly. The TCFA consists of several different checks that are performed by the on-duty meteorologist of the system and its surroundings. If the condition being checked is met, a certain number of points are given to the system. Parts of the TCFA Section 1 The first section of the TCFA contains information on the area of the alert as well as the estimated center of the circulation. The estimated maximum sustained winds are provided as well. Section 2 The second section generally contains more specif ...
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Wind Shear
Wind shear (; also written windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude. Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on ...
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