Comparison of two methods of near-surface wind speed estimation in the 22 May, 2011 Joplin, Missouri Tornado

Abstract

Tornado research has significantly advanced our understanding of tornadoes and their impacts. However, knowledge of the near-surface (<10m above ground) wind speeds in tornadoes is still lacking, despite its importance to both the engineering and meteorological communities. Because near-surface wind speeds in tornadoes are typically out of the reach of radar, and in-situ measurements are difficult to obtain, the peak near-surface wind speeds are currently estimated using methods based upon the damage inflicted. In this study, a near-surface wind field model is developed using tree-fall patterns observed following the 22 May, 2011 Joplin, Missouri tornado. This wind field is compared to over 1200 individual wind speed estimates throughout the tornado path, obtained from a ground survey of the building damage using the Enhanced Fujita (EF) scale. The comparison demonstrates for individual structures that the estimated tree-fall wind speeds are consistently higher than wind speeds estimated using the EF scale. Differences between the two methods become more pronounced for individual structures closer to the tornado center.