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The May 2007 tornado outbreak was an extended tornado outbreak that started on May 4, 2007, affecting portions of the Central United States. The most destructive tornado in the outbreak occurred on the evening of May 4 in western Kansas, where about 95% of the city of Greensburg in Kiowa County was destroyed by an EF5 tornado. The supercell killed at least 13 people including 11 in Greensburg and two from separate tornadoes.〔 〕〔CNN, (Storm-hit Kansas residents return home ) 6:30 am EDT, May 8, 2007, retrieved 7:50 am EDT, May 8, 2007.〕 At least 60 people were injured in Greensburg alone. It was the strongest tornado of an outbreak which included several other tornadoes reported across Oklahoma, Colorado, Kansas and South Dakota that occurred on the same night. 25 tornadoes were confirmed that night. The outbreak did not end there; a total of 84 tornadoes were confirmed reported on May 5 in the same area. Most were in open country but one fatality was reported in Ottawa County, Kansas near a county lake. Fourteen more tornadoes were confirmed on May 6 in the same general area before the activity subsided. ==Meteorological synopsis== This severe weather outbreak can be traced back to a powerful, slow-moving low pressure area with a warm front to the north over Nebraska and Missouri.〔(【引用サイトリンク】title=Daily Weather Maps, Saturday May 5, 2007 )〕 On May 4, the low stalled over the High Plains and additional moisture coming from the Gulf of Mexico moved in behind the warm front and increased amounts of instability across much of the region, with CAPE values as high as 5,500 J/kg. In addition, the dry line, which marks a divided line between the dry and humid air mass, was positioned over the southern High Plains. This allowed for the initiation of scattered supercells on May 4. High wind shear also allowed for intense rotation in the atmosphere. All the ingredients were present for the developing of supercell thunderstorms producing damaging wind, large hail and tornadoes. The Storm Prediction Center issued a moderate risk for severe weather across western Kansas and small portions of Oklahoma, Colorado and Nebraska for May 4, while temperatures were in the mid to high 80s°F (near 30 °C). The atmosphere remained capped for much of the day, but storms began to develop in the late afternoon hours in western Oklahoma and the eastern Texas Panhandle. The most intense supercells developed in the early evening hours across northwestern Oklahoma and southwestern Kansas. They eventually produced 25 tornadoes, including the devastating Greensburg tornado and three other extremely large tornadoes which followed the Greensburg tornado late that evening.〔(【引用サイトリンク】 Tornado Watch 227 )〕 The supercells remained intact well into the overnight hours as the extremely unstable air mass precluded rapid dissipation expected with the loss of daytime heating which would normally be expected in the Plains. The last tornado of the night did not lift until shortly after 2:00 a.m. early on May 5.〔 On May 5, the SPC issued a high risk of severe weather for Central Kansas and central Nebraska, while moderate and slight risks for severe weather extended for areas far beyond.〔(【引用サイトリンク】 May 5, 2007 1300 UTC Day 1 Convective Outlook )〕 The low pressure system in place moved northward, but the extending front had barely moved.〔(【引用サイトリンク】 Daily Weather Maps, Sunday May 6, 2007 )〕 The storms were quick to develop. Severe weather reports were already coming in by late morning, and the first tornado reports came in during the early afternoon hours. The most intense activity took place during the late afternoon and evening hours as supercells developed along a long line from South Dakota to North Texas. Over 80 tornadoes were confirmed that day, along with hail as large as softballs and straight–line winds as strong as 90 mph (145 km/h).〔 The activity weakened in the late evening, but not before the last tornadoes were reported in Iowa in the overnight hours. The low gradually weakened and became less conducive for severe weather development on May 6. Nonetheless, the SPC issued a moderate risk for severe storms over parts of central Kansas and northern Oklahoma as the trough remained in place.〔(【引用サイトリンク】May 6, 2007 1300 UTC Day 1 Convective Outlook )〕 The activity was far less than on the two previous days, however there were still several additional tornadoes across the Plains (all of them weak, mostly EF0). The system finally left the area on May 7 and did not produce any more significant severe weather. 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 2007 tornado outbreak」の詳細全文を読む スポンサード リンク
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