Analysis of a nontornadic storm during VORTEX 95

Analysis of a supercell storm that did not produce a tornado near Hays, Kan sas, is presented. A well-defined midlevel mesocyclone was apparent through out most of the storm's life cycle. Numerous shallow circulations were obse rved along the rear-Rank gust front during the data collection period. Six of these circulations strengthened into intense low-level mesocyclones. Eac h of these mesocyclones failed to produce a tornado. The strongest low-leve l mesocyclone, referred to as vortex #4, underwent a life cycle that was co nsistent with other tornadic mesocyclones documented in the literature. The se results illustrate that the presence of a long-lived mesocyclone at low levels is not sufficient for tornadogenesis to occur. The kinematic structure of the low-level mesocyclone that did not produce a tornado is compared with a tornadic mesocyclone from another storm in orde r to understand the characteristic differences between these circulations. The results lead to the conclusion that the presence of a low-level mesocyc lone, occlusion downdraft, and updraft/downdraft structure that spirals cyc lonically around the circulation are not sufficient conditions for tornadog enesis. Retrieved perturbation pressure and buoyancy fields are used to exa mine the forcing mechanism of the occlusion downdraft. A downward-directed pressure gradient appears to be the primary forcing mechanism of this downd raft. Perturbation temperature retrievals suggest that the occlusion downdr aft is accompanied by a warm core.