Trajectories Within the Weak Echo Regions of Hailstorms

Abstract

Three-dimensional tracks of 21 slow-fall chaff packets have been obtained while the packets were rising in the weak echo regions of eight separate Colorado hailstorms. The chaff packets were released at cloud base in the strong smooth updrafts and tracked with a M-33 track radar. In many cases the chaff was released from an instrumented aircraft. From these data it is shown that the inflow air often has its origin near the surface, the inflow air is typically negatively buoyant below cloud base, there exists a significant non-hydrostatic pressure perturbation in most severe storms, and a vertical velocity maximum typically exists within the weak echo region.