Abstract
Detailed analyses of radar echoes, betanetwork data and upper-air soundings recorded on 3 April 1964 are made to investigate possible mechanisms of the movement of severe thunderstorms. One of the storms investigated moved significantly to the left of the mean wind while others moved in the direction of or moderately to the right of the mean wind. The left-moving storm was found to generally display a mirror image of the radar echo intensity structure, growth, and circulation character of right-moving storms. A similar relationship is found in the surface pressure and wind fields. Analyses of a diverging storm pair revealed that the left-moving storm echo indicated the presence of continuous echo growth and development along the left flank of a quasi-steady supercell. An area of low surface pressure, and converging surface wind occurred along the left-front quadrant beneath a low-level inflowing current. The right-moving storms were found to contain similar pressure and wind features along the right-rear flank. The analytical results give reasonable evidence that continuous propagation was occurring on opposing flanks of the storm pair. The continuous propagation mechanism, incorporated in a simple, qualitative model taking into account low-level momentum conservation, drag, and lift is demonstrated to be important in order to explain the observed movement of these storms.
