| Data were presented for three High Plains thunderstorms in which penetrations were made of the weak echo region by an instrumented aircraft. Two of the storms were steady state, as revealed by chaff analysis and subsequent subcloud passes. Thus, changes to the updraft were spatial. The third storm dissipated after the penetrations were begun, such that the observed changes were spatial, temporal or both. The three storms were each characterized by a negatively buoyant cloud base. Chaff released into the updrafts of the storms did not decelerate. A positive pressure perturbation gradient, therefore, existed within the weak echo region.;The analysis of the equivalent potential temperature fields for the two steady storm cases revealed considerable entrainment of environment air into the weak echo region. The mixing of the entrained parcels caused an increase of turbulence with height. |
