Flow in Severe Thunderstorms Observed bu Dual-Doppler Radar

Abstract

Dual-Doppler (S-band) radar observations are used to describe both the three-dimensional flow and a fife cycle of a severe thunderstorm on 6 June 1974. The primary updraft region was near a small mesocyclonic circulation located on the storm's right (southern) flank. Rotation was first noted aloft (between 3 and 5 km elevation) and lowered with time. During the mature stage, major downdrafts were found on the storm's western edge and within the left forward (northeastern) quadrant. Outflow from both downdrafts combined near the cloud base to form a vigorous gust front. Hook echo formation is attributed to horizontal acceleration of low-level droplet-laden air as the downdrafts intensified and the outflow interacted with the inward-spiraling updraft.