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The June 16–18, 2014 tornado outbreak was a tornado outbreak concentrated in the Great Plains and the Midwestern United States. Two tornadoes also occurred in Ontario. The severe weather event most significantly affected the state of Nebraska, where two twin EF4 tornadoes 〔(【引用サイトリンク】url=http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=oax&storyid=102897&source=0 )〕 killed two and critically injured twenty others in and around the town of Pilger on the evening of June 16. The two Pilger tornadoes were part of a violent tornado family that produced four consecutive EF4 tornadoes and was broadcast live on television.〔 The outbreak went on to produce multiple other strong tornadoes across the northern Great Plains states throughout the next two days. ==Meteorological synopsis== On June 13, 2014, the SPC noted the possibility of severe weather associated with potential mesoscale convective systems in the northern United States for June 16–18. However, the predictability of this event was too low for the SPC to designate areas as under risk of severe weather. The following day, the SPC revised their forecasts, indicating a slight risk for severe activity for areas around the confluence of the Big Sioux and Missouri rivers two days before the eventual tornado outbreak. The development of a low-pressure area and increasing atmospheric instability were expected to be contributing factors. Forecasts remained relatively unchanged on June 15, though the probability for "significant severe weather" was predicted for a large area of northern Iowa and adjacent areas. The morning of June 16 was marked only by isolated storms in the Nebraska area with only marginal severe weather. Beginning at around 0800 UTC, however, favorable conditions for severe weather, particularly for large hail, began to build across central Nebraska. Moisture from the Gulf of Mexico began to make its way into southern Nebraska and over Kansas, raising dew points over the region. In addition, the prevalence of altocumulus castellanus clouds was an indicator for additional severe weather later in the day. The flow of moisture into the region was further enhanced by an eastward progressing warm front, and at 1200 UTC on June 16, the SPC once again issued a slight risk for severe weather for the eastern halves of South Dakota, Nebraska, and extending eastward into the western Great Lakes region. This was followed shortly after by the day's first severe thunderstorm watch, issued for primarily eastern Nebraska in response to a developing line of supercells. An hour later, the SPC upgraded some areas previously under a slight risk for severe weather to a moderate risk as a result of continuously increasing moisture content and CAPE in the atmosphere. At 1613 UTC, the SPC issued the first of three public severe weather outlooks for the day, covering a region centered on Sioux City, South Dakota. A Particularly Dangerous Situation tornado watch was issued later that afternoon, and a powerful cyclic supercell developed in Nebraska. This supercell went on to produce a family of six tornadoes, including four EF4s that affected areas in and around Stanton, Pilger, and Wakefield, Nebraska. Two fatalities occurred in or near Pilger and much of the town was destroyed.〔 Later that evening, two tornadoes (rated EF1 and EF2) struck the town of Platteville, Wisconsin simultaneously, resulting in major damage.〔http://www.crh.noaa.gov/arx/?n=jun1614〕 Tornado activity continued on the 17th, with an early morning EF3 causing major damage to homes and an elementary school in Verona, Wisconsin, and an EF2 from the same storm causing damage in residential areas of Madison.〔http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=mkx&storyid=102885&source=0〕 Later that day, an EF3 tornado caused significant damage in rural areas of Carter County, Montana near the Custer National Forest. A large EF2 tornado also caused damage to numerous homes in Angus and Barrie, Ontario.〔http://www.citynews.ca/2014/06/17/tornado-touched-down-in-angus-environment-canada/〕〔http://barrie.ctvnews.ca/environment-canada-ef-2-tornado-tracked-from-angus-to-barrie-1.1874646〕 Later that evening, multiple large wedge tornadoes were reported near the towns of Coleridge and Laurel, Nebraska.〔http://www.spc.noaa.gov/climo/reports/today.html〕 One of these tornadoes caused EF3 damage to farms and trees outside of Coleridge. On the night of June 18, an EF2 tornado hit the South Dakota town of Wessington Springs, trapping some of its residents in their homes. 43 homes and 12 businesses in town were damaged or destroyed. Another pair of twin tornadoes were also reported, near the South Dakota community of Crow Lake. A large multiple-vortex tornado completely destroyed a farm near the town of Alpena later that evening.〔http://www.ksfy.com/story/25833210/farm-near-alpena-completely-demolished-by-tornado〕 That tornado was rated an EF4, the fifth of the outbreak sequence. Overall, the outbreak resulted in 77 tornadoes, two fatalities, and numerous injuries. 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「June 16–18, 2014 tornado outbreak」の詳細全文を読む スポンサード リンク
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