Super-resolution polarimetric observations of a cyclic tornadic supercell

Recent developments have shown that WSR-88D radars are capable of collecting data in “super-resolution” mode. Super-resolution data are sampled every half degree in azimuth with 250-meter gate spacing. For the first time, super-resolution polarimetric data have been collected for a cyclic tornadic supercell storm that occurred in north-central Oklahoma on 24 May 2008. The data were obtained by the NSSL research prototype dual-polarization WSR-88D radar (KOUN). The storm, which displayed high-precipitation supercell characteristics, produced at least ten tornadoes, one of which was rated EF-2 and was about one mile wide.

An overview of the environment in which the storm developed is presented. On the synoptic scale, the environment was characterized by extremely high CAPE and moderate shear. Mesoscale features captured by the Oklahoma Mesonet are analyzed, and their role in the initiation and enhancement of the storm are discussed. The KOUN data from the storm exhibit supercell polarimetric signatures in high resolution, including the tornadic debris signature, Z_DR arc, Z_DR and K_DP columns, and midlevel rings of enhanced Z_DR and reduced ρ_HV. These signatures are discussed in the context of storm evolution. We also present implications of the availability of super-resolution polarimetric data following the national upgrade of the WSR-88D network.