High-resolution Ensemble Analysis and Prediction of the 19 May 2013 Norman-Shawnee Supercell and Tornadic Circulation

On 19 May 2013, two tornadic supercells impacted the Oklahoma City metropolitan area. One of these supercells developed from a southern complex of storms that initiated just west of Norman. The supercell became tornadic over Lake Thunderbird around 23 UTC then produced EF-4 damage near Shawnee. Importantly, an unusually high-quality Doppler radar dataset exists from the tornadogenesis phase of the Norman-Shawnee storm. Tornadogenesis was observed by five Doppler radars (KOUN, KTLX, TOKC, MPAR, and NOXP) at very close range (~ 20 km, see Figure 1), yielding very high-resolution observations from a variety of viewing angles. Moreover, TOKC, MPAR, and NOXP collected partial low-level volumes at 1-1.5 min frequencies, and KOUN, NOXP, and KTLX collected dual-polarization radar data. The exceptionally high-resolution radar data, combined with a sequence of soundings from the MPEX experiment, presents a unique opportunity to initialize a high-resolution ensemble (Dx ~ 200 m) and attempt to predict the evolution of sub-mesocyclone scale features such as the circulation that produces the EF-4 tornado east of Lake Thunderbird.