THE GARDEN-CITY, KANSAS, STORM DURING VORTEX-95 - PART-I - OVERVIEW OF THE STORMS LIFE-CYCLE AND MESOCYCLOGENESIS

Analysis of a supercell storm that produced an F1 tornado near Garden City, Kansas, is presented. This event provided one of the first oppor tunities to synthesize data collected by a new airborne radar platform called ELDORA (Electra Doppler radar) developed by the National Cente r for Atmospheric Research. The early stages of development of the mid level mesocyclone and the entire evolution of the low-level mesocyclon e are captured over a 70-min period. The low-level mesocyclone began a s an incipient shallow circulation along a synoptic-scale trough. The circulation intensified and grew in depth via vortex stretching under the influence of a strong updraft. As this rotation built up from the boundary layer, it initially remained separate and distinct from the m idlevel mesocyclone. Subsequently, the two mesocyclones merge to produ ce a single column of rotation 4-5 km in diameter. An occlusion downdr aft develops within the mesocyclone circulation during the last passes by the storm signaling the beginning of the tornadic phase. Perturbat ion pressure retrievals provide conclusive evidence that this downdraf t is driven by a downward-directed pressure gradient force.