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The May 21–26, 2011 tornado outbreak was a deadly tornado outbreak across the Midwestern and Southern regions of the United States. Most of the tornadoes developed in a corridor from Lake Superior southwest to central Texas; isolated tornadoes occurred in other areas. An especially destructive tornado destroyed one-third of Joplin, Missouri, resulting in 158 deaths and 1000 injuries.〔(【引用サイトリンク】title=Storm Event Survey )〕〔(【引用サイトリンク】title=City official: Joplin tornado death toll at 153 )〕 The Joplin tornado is the deadliest in the US since April 9, 1947, when an intense tornado killed 181 in the Woodward, Oklahoma area. Tornado-related deaths also occurred in Arkansas, Kansas, Minnesota, and Oklahoma. Overall, the tornado outbreak resulted in 184 deaths, 6 of those non-tornadic, making it second only to the 2011 Super Outbreak as the deadliest since 1974, and the second costliest tornado outbreak in US history behind that same April 2011 outbreak, with insured damage estimated at $4–7 billion.〔 ==Meteorological synopsis== April 2011 was the most active month for tornadoes on record, capped by a very large tornado outbreak (the largest on record) that killed 324 people in the final week. In contrast, the first three weeks of May were remarkably quiet; only a few isolated tornadoes were confirmed. However, that pattern changed abruptly as a strong low pressure area and associated dry line and cold front tracked eastward. On May 21, a small system of thunderstorms developed in Brown County, Kansas while another system formed to the southeast of Emporia, Kansas. The Brown county system spawned a brief tornado over Topeka, Kansas, causing minor damage. This system also caused significant damage in Oskaloosa, Kansas, and other communities. Meanwhile, the Emporia system spawned an EF3 tornado that struck Reading, Kansas; one person was killed, several others were injured, and at least 20 houses were destroyed. These two systems developed several other tornadoes throughout the evening. A moderate risk of severe weather was issued for much of the Midwest, as well as further south to Oklahoma for May 22. The first tornadic supercell developed in the mid-afternoon hours over the western Twin Cities in Minnesota, and caused moderate damage in the Minneapolis area. Shortly thereafter, an intense tornado crept towards Harmony, Minnesota, prompting the National Weather Service to issue the first tornado emergency of the outbreak. Late that afternoon, a large, intense EF5 multiple-vortex tornado left catastrophic destruction in Joplin, Missouri. Causing 158 fatalities, it was the deadliest single tornado in the U.S. since at least 1947. Once again, a moderate risk of severe weather was issued on May 23—this time for the southern Plains and the lower Great Lakes. Forecasts showed that the main threats would be damaging wind and large hail instead of frequent tornadoes; the stationary front lacked the necessary wind shear to sustain the type of tornadic supercells seen on May 22. This prediction came to light, as only scattered, and mostly weak tornadoes were reported throughout the day. However, an EF2 tornado caused significant damage in Tennessee and Kentucky. On May 24, a high risk of severe weather was issued for parts of south-central Kansas, central and eastern Oklahoma, and extreme north-central Texas; a moderate risk was issued for surrounding areas in those three states plus northwestern Arkansas and southwestern Missouri. Throughout this region, strong to violent tornadoes were considered to be highly probable for three reasons: (1) the stationary front was expected to maintain its position over the region, (2) wind shear was expected to greatly increase, and (3) these elements would be associated with an incoming trough. Late that morning, the tornado threat increased to 45%, a rare occurrence matching the widespread April 27 outbreak. At 12:50 p.m. CDT, the SPC issued a Particularly Dangerous Situation Tornado Watch for parts of central Oklahoma, including Oklahoma City and northern Texas, in effect until 10:00 p.m. CDT. Numerous tornadoes touched down in several regions, with the first activity being in western Oklahoma that afternoon where several very intense tornadoes developed, including another EF5 (the sixth of the year). They did not cause extensive damage in Oklahoma City, but 11 deaths were reported among extensive damage just to the southwest of the OKC metro. Other tornado clusters developed in central Kansas that afternoon and in the Dallas-Fort Worth Metroplex that evening. Once again on May 25, a high risk of severe storms was issued for the middle Mississippi River valley from near Memphis, Tennessee northward to north of Evansville, Indiana, and was expanded late that morning northward to near Indianapolis, Indiana, northwest to near St. Louis, Missouri, southeast to just west of Nashville, Tennessee and southwest to near Little Rock, Arkansas. Several hours before the outbreak was set to begin, a PDS Tornado Watch was issued for western Kentucky, southern Indiana, the southern half of Illinois and eastern Missouri. The entire state of Indiana, southern Michigan, and most of Missouri were under tornado watches. Widespread tornado activity occurred that day across the central and eastern US. An EF3 destroyed many homes in the town of Bedford, Indiana, and an EF2 wedge tornado caused severe damage in Sedalia, Missouri. Tornado activity continued on May 26, but most were weak. 8 separate EF1 tornadoes touched down across Pennsylvania. An isolated EF3 tornado destroyed multiple homes near Bush, Louisiana. 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「May 21–26, 2011 tornado outbreak sequence」の詳細全文を読む スポンサード リンク
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