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This page documents the tornadoes and tornado outbreaks of 2013. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia. There were at least 903 tornadoes confirmed in the United States in 2013. 113 fatalities have been confirmed worldwide in 2013: 55 in the United States, 31 in Bangladesh, 24 in China and three in Turkey. On April 1, Canada began utilizing the Enhanced Fujita scale to rate tornadoes with minor modifications to better suit the region's tornadoes. ==Synopsis== Entering 2013, the Oceanic Niño Index (ONI) for the three-month period lasting from November 2012 to January 2013 based on sea surface temperature (SST) anomalies was -0.3, denoting cooler than normal SSTs in areas of the Pacific. Throughout early to mid-January in the United States, there was isolated tornado activity, centered primarily in the South. In late-January, an unusually strong upper-level trough combined with atmospheric instability produced a widespread tornado outbreak over the Southern United States.〔 The strongest of these tornadoes was an EF3, the first intense tornado confirmed in the U.S. in 2013.〔 In eastern Australia, the remnants of Tropical Cyclone Oswald produced significant flooding in conjunction with tornadoes in late January.〔 A small outbreak on February 10 spawned an EF4 tornado that affected Hattiesburg, Mississippi. A period of inactivity followed the early weeks of the year. Both March and April had near-record low activity, which was attributed to cold air persisting over much of the continental U.S., preventing any significant severe weather from occurring (and allowing for late-season winter storms). However, this pattern changed abruptly in mid-May as a significant outbreak struck towns in north-central Texas, followed closely by a much larger outbreak that affected much of the Midwestern and Southern U.S., especially in Oklahoma. On May 20, an EF5 tornado struck Moore, Oklahoma. Another powerful outbreak struck the Midwest and Ark-La-Tex area in the final week of May. The outbreak produced an EF3 just west of Oklahoma City that hit areas just south and southeast of El Reno on May 31, killing storm chaser Tim Samaras and his two partners and injuring The Weather Channel's Mike Bettes' Tornado Hunt team. June and July were both below average for tornadoes, and August and September were generally near average for tornadoes. Early October featured a very small outbreak of tornadoes over Nebraska and Iowa; however, two of the tornadoes were violent enough to be rated EF4. Another small outbreak with mostly weak tornadoes ended the month, pushing October activity to near average. After a lull in activity during the first half of November, a large outbreak occurred on November 17, producing 73 tornadoes and killing seven people. Overall, November was slightly above average for tornadoes. December was below average for tornadoes, with only 13, causing 2013 to end with a record low tornado count with adjustments made for undercounting tornadoes in earlier years.〔(【引用サイトリンク】url=http://www.spc.noaa.gov/wcm/adj.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「Tornadoes of 2013」の詳細全文を読む スポンサード リンク
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