Tornados are severe storms that occur randomly. In the contiguous United States close to 1,000 tornadoes occur each year. Since the storms are short lived and cover relatively small areas, it has not been possible to record wind speeds in tornadoes with instruments near the ground. Documentation of damage and pattern of tree-fall give indication of winds in tornadoes. The intensity of a tornado is judged by the National Weather Service by assigning a number on the EF scale, which is based on building damage. More knowledge is needed about winds in tornadoes near ground so the buildings and structures can be designed to resist these storms. The EF4 intensity tornado that occurred in Arkansas can provide data on near ground winds as the tornado tracked over hilly terrain.
This Rapid Research Grant (RAPID) project plans to assemble damage data of buildings and trees in the field along the 41 mile long track of the tornado that occurred on April 27, 2014 in hilly terrain in Arkansas. The hypothesis is that tornado wind speed at ground level increases going uphill and decreases on downhill side as the tornado interacts with hilly terrain. Since it has not been possible to measure wind speeds in tornadoes at ground level with instruments, damage to buildings and trees provide a good indication of winds. The field data will include photographs taken from air as well as from ground, Google Earth signature of the terrain, radar data, and other data that may be available from media. The gathered data will be organized along with preliminary analysis for initial verification of the hypothesis. The data will be useful to researchers who are pursuing computational simulation of tornado vortex as well as to investigators who are pursuing physical simulation in wind tunnel.
