Finestructure of the Del City-Edmond Tornadic Mesocirculation

Interrelationships among severe thunderstorm wind flow, tornado parent circulation and tornado are examined with dense single- and dual-Doppler radar observations from the Del City-Edmond, Oklahoma, storm of 20 May 1977. Beginning with tornadogenesis, rising inflow air from right-hand quadrants and subsiding air from a developing downdraft on the storm's rear are wrapped in a large spiral pattern about the tornado. The updraft appears to drive the tornado while the downdraft appears to form as entrained environmental air, concentrated by the intensifying parent circulation, is cooled evaporatively.