A cyclic, tornadic supercell on 10 May 2010: Analysis of a VORTEX2 case

On May 10 a very strong, cyclic supercell formed in central Oklahoma and moved across eastern Oklahoma to the Arkansas border. Along the way it produced 20 different tornadoes associated with at least 11 different mesocylones during a 4-hour period. A portion of the VORTEX2 armada intercepted the storm in east-central Oklahoma, capturing data on the occluding/dissipating stage of one mesocyclone and accompanying tornado (EF3), and the cyclic formation of another mesocyclone with an accompanying tornadogenesis event (EF1). Single- and multiple-Doppler analyses from the NOAA (NSSL) X-band dual-polarization radar (NOXP), the University of Massachusetts X-band dual-polarization radar (UMXP), and the Naval Postgraduate School Meteorological Weather Radar-2005 X-band phased-array radar (MWR-05XP) will be presented. Radar siting locations in hilly terrain caused partial beam blockage at lower elevation angles. Analysis techniques to compensate for the blockage, including use of Specific Differential Phase (Kdp; resistant to partial-beam blockage) will be explained. Results include the observation of a strong occlusion downdraft within the dissipating mesocyclone that disrupts/weakens the initially strong horizontal wind field and leads to tornado dissipation. The new mesocyclone forms along a confluent updraft zone associated with the storm rear-flank gust front. With time, the confluent flow and increasing low-low rotation produce a classic hook echo. Tornadogenesis occurs as a new zone of rear-flank downdraft develops and increases rear-to-front, low-level flow. Dual-polarization variables indicate the old occluding hook echo and newly developing hook echo are both fully composed of rain. No hail is observed within the storm right flank up to a height of 3.5 km (top of the data) at any time during the observed evolution.