THREE-DIMENSIONAL PRESSURE PATTERN OF THE DALLAS TORNADO AND SOME RESULTANT IMPLICATIONS

The three-dimensional pressure field of the Dallas tornado, April 2, 1957, is integrated from a distribution of observed tangential wind speeds. A total pressure drop of 60 mb. is computed at ground level at the axis. Variations in tornado funnel geometry are explained by changes in moisture content of the involved air and system-wide pressure changes. The effects of the moving pressure field on hypothetical vented and unvented buildings are computed. The results indicate that a dwelling, which could lose in 5 seconds about 75 percent of an imposed pressure difference, would most likely not yield due to internal pressure alone, if the imposed pressure difference were like that of the Dallas tornado.