Dual-Doppler and Multiparameter Radar Observations of a Bow-Echo Hailstorm

Abstract

Abstract During the afternoon and evening hours of 23 May 1991 a hail-producing multicellular severe thunderstorm developed near Denver, Colorado, and tracked eastward for more than 100 km. Along this path, hailstone diameters of 2–7 cm (0.75–2.75 in.) were reported at several points. The storm was observed by both the CSU-CHILL (CHL) and NCAR Mile High (MUR) 10-cm Doppler radars. The general echo morphology evolved by way of cyclic, discrete new cell formation near an outflow boundary moving ahead of the storm's forward flank. As this new cell growth occurred, the shape of the storm's most intense core also evolved in a periodic fashion. On four separate occasions these cores briefly assumed a bow shape with peak reflectivity values of 65–70 dBZ. The evolution of one such bow echo was examined by a series of six CHL-MHR dual-Doppler analyses. The resultant airflow patterns suggested that the core reflectivity structure was deformed into the bowlike configuration by updraft-induced flow field perturbation...