Observed and Numerically Simulated Structure of a Mature Supercell Thunderstorm

• Published in: Journal of the atmospheric sciences 1981-08, Vol.38 (8), p.1558-1580
• Main Authors: Klemp, J B, Wilhelmson, R B, Ray, P S
• Format: Article
• Language: English
• ISSN: 0022-4928; 1520-0469
• DOI: 10.1175/1520-0469(1981)038<1558:oansso>2.0.co;2

Through the interactive use of Doppler radar analyses and a three-dimensional numerical storm simulation, the detailed structure of a supercell tornadic storm is analyzed. This storm (the Del City storm) occurred in central Oklahoma on May 20, 1977. The storm exhibited certain important features essential to maintaining its longevity, which promote the storm's transition to its tornadic phase. These features were strongly influenced by the rotational character of the storm, which separated the precipitation from the updraft and oriented the resulting downdrafts to reinforce low-level convergence along the gust front and sustain the storm. Analyses of air parcel and rain trajectories within the storm provide a detailed visualization of this internal structure. These trajectories reveal that air parcels rising through the cyclonically rotating updraft actually turn anticyclonically with height because of the influence of the storm-relative environmental wind field. Downdraft trajectories suggest that the cold outflow air behind the gust front originates in the environment at heights below 2 km. The distribution of vorticity is also investigated within the mature storm. At low levels, the strong cyclonic vorticity is found to be located downwind of the convergence line, along the strong gradient between the updraft and downdraft. The similarities in structure between the observed and simulated storm suggest that the larger scale environment plays a dominant role in structuring many of the detailed features of the storm.