Observations of a storm containing misocyclones, downbursts, and horizontal vortex circulations

Abstract

One misocyclone (<4km scale) is particularly intense with a peak vorticity of ≃100 × 103 s-1 near cloud base. Despite the intense rotation, no tornadoes or funnels were observed and no damage was reported. Pressure perturbation analysis does not show any evidence for strong, downward-directed pressure gradient forces below cloud base that would act to accelerate a downdraft. The downdraft is observed to accelerate below cloud base. Observations and buoyancy estimates calculated from radar refelctivity show negative buoyancy is playing a role in downdraft intensification. Dynamical forces may be playing a role in accelerating the downdraft above cloud base. Horizontal vortex circulations, or rotors, form along the edge of the misocyclone and downdraft and propagate away from their source region. Strongest surface winds are associated with the rotors. An explanation of these circulations is important since they seem to have been involved in the Dallas-Fort Worth Regional Airport crash of an L-1011 jet. -from Authors