The Hybrid Multicellular–Supercellular Storm—an Efficient Hail Producer. Part I: An Archetypal Example

Abstract

Abstract This is the first of a two part series describing storms termed hybrid” because their characteristics are intermediate between those classically defined as multicellular and supercellular. They are important because they tend to produce more hail and, in fact, often produce the most severe hailfalls in the central Oklahoma area. Part I discusses the structure and hail growth characteristics of an archetypal example as derived from Doppler radar and surface hail collections. The storm produced maximum diameter hail of 75 mm and a hailswath that was about 300 km long and, at one point, 40 km wide. Although the storm had the large-bounded weak echo region and generally steady appearance associated with supercellular storms, the data suggest that at any time there were three updrafts separated by a distance of 5 to 8 km. Another distinctive flow feature is an intense downdraft in an area of weak reflectivity to the west of the updraft. Hailstone embryos collected over a distance of 100 km and 1.5 h ...