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The April 15–16, 1998 tornado outbreak was a two-day tornado outbreak that affected portions of the Midwestern United States, Mississippi and Tennessee Valleys on April 15 and April 16, 1998, with the worst of the outbreak taking place on the second day. On that day, 13 tornadoes swept through Middle Tennessee—two of them touching down in Nashville, causing significant damage to the downtown and East Nashville areas. Nashville became the first major city in nearly 20 years to have an F2 or larger tornado make a direct hit in the downtown area.〔 In addition, the outbreak produced several other destructive tornadoes in Middle Tennessee. One of them, southwest of Nashville, was an F5 tornado—one of only two (the only official one) ever recorded in the state (the other, unofficial however, being in Pinson, Tennessee in 1923). That tornado remained mainly in rural areas of Wayne and Lawrence counties.〔 Other tornadoes during the 2-day outbreak struck Arkansas, Alabama, Illinois, and Kentucky. 12 people were killed by tornadoes during the outbreak: two in Arkansas, three in Kentucky, and seven in Tennessee (one in Nashville, three in Wayne County, and three more elsewhere). This tornado outbreak occurred at the end of the record-setting 1997–1998 El Niño event. ==Meteorological synopsis== One week after the Birmingham tornado outbreak took place across Alabama and Georgia on April 8–9, 1998 and several other states on April 7, a similar pattern developed across the Midwest and southeastern United States starting on April 16, 1998. A very strong low pressure system developed across the central part of North America and was associated with a long cold front. Ahead of the storm, the warm moist air generated from the Gulf of Mexico increased the likelihood for a significant weather event. On April 15, activity developed across the Mid-Mississippi Valley and southern Ohio Valley where several tornadoes touched down in Illinois starting in the late afternoon before moving into Arkansas during the overnight hours where the first fatalities were reported. On April 16, as the main low pressure system was near the Great Lakes and its cold front crossing the Mississippi River, dew points reached the mid to upper 60s across the Tennessee Valley while later in the day, CAPE values reached 1600 J/kg while dry air intrusion was also on the rise increasing the threat of severe weather across the area. As the bulk of the supercells moved out of Arkansas, the tornadic activity was slower during the morning hours before re-intensifying west of Nashville early in the afternoon. Major tornadoes struck from southern Tennessee to southern Kentucky with additional storms as far north as Michigan and several other storms in Alabama across Walker and Cullman Counties, which was slightly north of the areas that were hardest hit by the previous outbreak. 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「April 15–16, 1998 tornado outbreak」の詳細全文を読む スポンサード リンク
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