Airflow and Hail Growth in a Severe Northern High Plains Supercell

Abstract Air and particle trajectory calculations using internal motions from Doppler radar observations are used to identify kinematic feature and hail growth processes operating in a supercell storm that occurred on 2 August 1981 in southeastern Montana. As the Rock Springs storm moved rapidly east-southeastward across the Cooperative Convective Precipitation Experiment (CCOPE) observational network, it produced a significant hailfall composed mostly of 2 to 3 cm diameter hailstones. Some diameters were as large as 6 to 10 cm. At least one funnel cloud was sighted, and there was extensive crop and property damage. In the hail growth model 1 to 5 cm hailstones were readily produced from frozen drops in the size range 50 μm to about 1 mm. Most of the hail apparently grew from frozen droplets that originated within either the upwind stagnation zone southwest of the main updraft core or the overhanging radar echo ahead of the updraft. Potential hailstone embryos entered the stagnation zone from a flanking c...