Nebraska Hit By Twin Twisters
June 17, 2014
A deadly double tornado struck Nebraska yesterday, causing 2 deaths and leaving at least 16 people injured. The two tornadoes touched down at the same time and traveled with about a mile (1.6 kilometers) between them. The small farming community of Pilger, Nebraska, about 60 miles (97 kilometers) southwest of Sioux City, Iowa, sustained heavy damage from the twisters. Monday’s storm system also brought damaging winds and rains to other Midwestern States, including Iowa, Minnesota, South Dakota, and Wisconsin. One area of South Dakota received more than a half-inch (1.27 centimeters) of rain in fewer than 3 minutes, flooding roads and interstates.
In addition to bringing high winds and rains, large, powerful thunderstorms can form deadly tornadoes. Such storms are called supercells. A supercell contains a rapidly rotating column of air called a mesocyclone. A smaller, swiftly rotating column of air called a funnel cloud can develop within the mesocyclone. If the funnel cloud reaches the ground, it becomes a tornado.
A tornado is a rapidly rotating column of air that can develop under a large, anvil-shaped thundercloud. Almost all tornadoes in the Northern Hemisphere rotate as shown in the diagram—counterclockwise when viewed from above (World Book illustration by Bruce Kerr).
Weather experts state that it is not uncommon for more than one tornado to form from a supercell. Usually, however, the first tornado shrinks and disappears as the second forms. Or, when two twisters form and both remain, there is usually one large, strong tornado and one smaller tornado. It is less common for the primary twister to keep going strong when a new twister forms, producing two tornadoes of the same strength at the same time. Nevertheless, that is what hit Nebraska Monday evening.
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