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A tornado warning (SAME code: TOR) is an alert issued by national weather forecasting agencies to warn the public that severe thunderstorms with tornadoes are possible, imminent, or occurring. It can be issued after a tornado or funnel cloud has been spotted by the public, storm chasers, emergency management or law enforcement, or more commonly if there are radar indications of tornado formation.〔(【引用サイトリンク】url=http://www.tornadofacts.net/tornado-safety-facts.php )〕 When this happens, the tornado sirens may sound in that area if any sirens are present, informing people that a tornado has been sighted or is forming nearby. The issuance of a tornado warning indicates that residents should take immediate safety precautions. It is a higher level of alert than a tornado watch, but (in the United States) it can be surpassed by an even higher alert known as a tornado emergency. ==Early history== The first official tornado forecast – and tornado warning – was made by United States Air Force Capt. (later Col.) Robert C. Miller and Major Ernest Fawbush, on March 25, 1948. The first such forecast came after the events that transpired five days earlier on March 20, 1948; Miller – a California native who became stationed at Tinker Air Force Base three weeks earlier – was assigned to work the late shift as a forecaster for the base's Air Weather Service office that evening, analyzing U.S. Weather Bureau surface maps and upper-air charts that failed to note atmospheric instability and moisture content present over Oklahoma that would be suitable for producing thunderstorm activity, erroneously forecasting dry conditions for that night. Thunderstorms soon developed southwest of Oklahoma City, and at 9:30 p.m., forecasters from Will Rogers Airport sent a warning to Tinker that the storm encroaching the city was producing wind gusts of and a "Tornado South on Ground Moving NE!" Base personnel received an alert written by the Staff Sarg. on duty with Miller, minutes before the twister struck Tinker several minutes later around 10:00 p.m., damaging several military aircraft (with total damage estimated at $10 million) that could not be secured in time before it crossed the base grounds. Following an inquiry the next day before a tribunal of five generals who traveled to Tinker from Washington, D.C., who ruled that the March 20 tornado was an "act of God() not forecastable given the present state of the art", base commander Gen. Fred Borum tasked Miller and Fawbush to follow up on the board's suggestion to consider methods of forecasting tornadic thunderstorms. Over the next three days, Miller and Fawbush studied reports and charts from previous tornado events to determine the atmospheric conditions favorable for the development of tornadic activity, in an effort to predict such events with some degree of accuracy. At the time, there had not been studies on how tornadoes formed; however, military radars were being adapted for forecasting use, allowing forecasters to see the outlines of storms but not their internal attributes such as rotation. Miller and Fawbush's findings on atmospheric phenomenon present in past outbreaks would aid in their initial forecast, as the day's surface and upper-air analysis charts determined the same conditions present on March 20 were present on the 25th, concluded that central Oklahoma would have the highest risk for tornadoes during the late-afternoon and evening.〔 Borum, who had put together a severe weather safety plan for base personnel, then suggested that Miller and Fawbush issue a severe thunderstorm forecast, and then asked the men if they would issue a tornado forecast based on the similarities between the conditions that produced the tornado which hit the base five days earlier, which they were reluctant to do. Fawbush wrote the forecast message that Miller would type and issued it to base operations at 2:50 p.m. as thunderstorms were approaching from North Texas. Defying the high odds of two tornadoes hitting the same area in five days, one hit the Tinker campus around 6:00 p.m., to the surprise of Miller (who left the base an hour earlier, believing their forecast would not pan out), who found out about the storm (produced by two thunderstorms that merged to the southwest of Tinker) via a radio report. Miller and Fawbush would not put out another tornado forecast until March 25, 1949, when they successfully predicted tornadic activity would occur in southeastern Oklahoma.〔 Miller and Fawbush soon would distribute their tornado forecasts to the American Red Cross and Oklahoma Highway Patrol, after giving William Maughan, chief meteorologist at the U.S. Weather Bureau's Oklahoma City office (who provided them with additional archived weather data to help fine-tune their forecasts), permission to relay their forecasts to those agencies. The relative accuracy of the forecasts restarted a debate over their reliability and whether military or civilian agencies should have jurisdiction over the issuance of weather warnings.〔 The USAF had pioneered tornado forecasting and tornado warnings, although John P. Finley had developed the first experimental tornado forecasts in 1885, before he and other officials with the agency were prohibited by the United States Signal Service's weather service from using the word "tornado" in forecasts two years later, directing Finley to instead reference "severe local storms", a move motivated by concerns by businessmen in the Great Plains that Finley's forecasts would hurt economic development if potential investors believed their areas were tornado-prone. This position on tornado forecasting would be shared with the U.S. Weather Bureau after it was formation in 1890, fearing that it would incite panic among the public if tornadoes were predicted to occur; the side effect of this was that the lack of warning resulted in a steady increase in the number of tornado-related fatalities through the 1950s, with some events prior to 1948 (such as the deadliest tornado in U.S. history, the Tri-State Tornado in March 1925, and the Glazier–Higgins–Woodward tornadoes in April 1947) having death tolls that exceeded well over 100. In 1938, the Weather Bureau rescinded its ban on the usage of the word "tornado" in weather products disseminated to emergency management personnel. The Bureau would develop a network of volunteer storm spotters in the early 1940s during World War II, to provide warning of tornadoes to workers in munitions plants and strategic factories.〔 The ban on issuing tornado warnings to the general public would not be revoked until Chief of Bureau Francis W. Reichelderfer officially lifted the ban in a Circular Letter issued on July 12, 1950 to all first order stations: "Weather Bureau employees should avoid statements that can be interpreted as a negation of the Bureau's willingness or ability to make tornado forecasts", and that a "good probability of verification" exist when issuing such forecasts due to the difficulty in accurately predicting tornadic activity. The American Meteorological Society agreed to have Miller and Fawbush present their methodology for forecasting tornadoes during the organization's 1950 meeting in St. Louis; after garnering press coverage for their successful prediction of past tornadoes, AMS representatives decided to open the presentation to the public.〔 The Air Force began issuing severe weather forecasts relayed to Weather Bureau offices and emergency personnel in tornado-prone regions through the formation of the Severe Weather Warning Center in 1951, before the Bureau's contention that the USAF intruded on its responsibility to relay such forecasts led to the SWWC limiting the release of its tornado forecasts to military personnel; however, the move to prohibit the USAF from widespread releasing of tornado forecasts led to disapproval and heavy criticism from Oklahoma media outlets, given the agency's continued refusal to provide public tornado warnings. The Weather Bureau issued its first experimental public tornado forecast in March 1952, which proved inaccurate and was released too late to become widely available for public consumption; however, a forecast issued the following evening managed to predict an outbreak of tornadoes across most of the warned seven-state area (from Texas to Indiana).〔 Even after the U.S. Weather Bureau lifted their ban on tornado warnings, the Federal Communications Commission continued to ban television and radio outlets from broadcasting tornado warnings on-air for the same reasoning cited in the Bureau's abolished ban. Broadcast media followed this ban until 1954, when meteorologist Harry Volkman broadcast the first televised tornado warning over WKY-TV (now KFOR-TV) in Oklahoma City, due to his belief that the banning of tornado warnings over broadcast media cost lives. Through an alert issued by the USAF Severe Weather Warning Center, Volkman opted to interrupt regular programming to warn viewers of a reported tornado approaching the Oklahoma City area; although station management and U.S. Weather Bureau officials were displeased with his move, WKY-TV received numerous telephone calls and letters thanking Volkman for the warning.〔(【引用サイトリンク】url=http://tulsatvmemories.com/weather.html )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「tornado warning」の詳細全文を読む スポンサード リンク
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