Dynamical Analysis of Outflow from Tornado-Producing Thunderstorms as Revealed by ATS III Pictures

Abstract

Detailed synoptic and dynamic analyses of outflow from tornado-producing thunderstorms of 23 April 1968 were made by using conventional rawinsonde data combined with ATS III pictures. It was found that the pre-existing flow at the cirrus level over storm areas changed dramatically into outflow as the storms developed. When the storms reached their mature stage, the horizontal dimensions of the outflow increased to ∼500 km, Detailed analyses of rawinsonde data inside the outflow area revealed the existence of a mid- tropospheric warm core accompanied by a significant field of convergence below the 700-mb surface. Quantitative analysis of the thermodynamical and dynamical aspects of the outflow field showed that the outflow was induced and maintained by convective warming.