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On March 2 and 3, 2012, a deadly tornado outbreak occurred over a large section of the Southern United States into the Ohio Valley region. The storms resulted in 41 tornado-related fatalities, 22 of which occurred in Kentucky. Tornado-related deaths also occurred in Alabama, Indiana, and Ohio. The outbreak was the second deadliest in early March for the U.S. since official records began in 1950; only the 1966 Candlestick Park tornado had a higher death toll for a tornadic system in early March. ==Meteorological synopsis== February 2012 was more active than normal in terms of the number of tornadoes, with a total of 50 confirmed. While the first three weeks of the month were unusually quiet, the pattern changed abruptly by a major tornado outbreak, which struck the region less than 72 hours prior to this storm, killing 15 people, including 8 in Harrisburg, Illinois alone, the result of an EF4 tornado. A moderate risk of severe weather was issued for March 2 a day in advance for a large area from near Tuscaloosa, Alabama to Dayton, Ohio as an intense storm system tracked across the region in a very high shear environment. Intense tornadoes were possible.〔 On the morning of March 2, it was upgraded and a high risk of severe weather was issued for Middle Tennessee and central Kentucky, later extended into Central and Southern Indiana and southern Ohio.〔 The Storm Prediction Center mentioned the potential for significant tornadoes.〔 Multiple PDS tornado watches were issued shortly thereafter.〔 The outbreak began fairly early in the morning, with an initial round of storms and tornadoes associated with the incoming warm front attached to a rapidly deepening low pressure area over the central Great Lakes. The initial round of storms allowed for a strong warm air mass to enter the region, with temperatures rising to near-record levels for early March and instability combining with extreme wind shear, resulting in a highly volatile air mass. As a result, a second, much larger broken line of discrete supercells developed and followed the Ohio River, with additional storms developing farther south. During the afternoon, those cells tracked eastward across the Ohio Valley, passing north of Louisville, Kentucky and south of Cincinnati, Ohio with devastating results. As isolated activity developed farther south, intense supercells also formed in central Kentucky in the late afternoon hours and tracked east into the Eastern Mountain Coal Fields region before weakening as they reached West Virginia later that evening. That area had the highest wind shear – with helicity values as high as 800 m2/s2 (despite lower instability) and that allowed the storms to spin violently, resulting in severe damage in several communities. The next day, on March 3, the cold front continued to push eastwards toward the United States East Coast, although the most severe activity took place near the Georgia-Florida state border.〔(【引用サイトリンク】url=http://www.wpc.ncep.noaa.gov/dailywxmap/index_20120303.html )〕 A slight risk of severe weather was issued for a small area extending from Cape Hatteras to the Mississippi Delta. A mesoscale convective system in South Carolina was responsible for hail reports in the area, although the threat for tornadoes was reduced with lower instability levels. Most tornado activity for the day was associated with an upper-level system in Florida, also causing damaging wind gusts. On March 4, most of the cold front responsible for the outbreak had already moved into the Atlantic Ocean with only a small portion of thunderstorms extending into Florida. A slight risk was issued for a section of Florida. Some scattered activity lingered around the East Coast for the duration of the day, but no additional tornadoes were reported. 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「March 2–3, 2012 tornado outbreak」の詳細全文を読む スポンサード リンク
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