Rapid-Scan, Dual-Polarization Radar Observations of Tornadic and Nontornadic Supercells in the Context of Forecaster Conceptual Models

National Weather Service forecasters employ scientific conceptual models to better anticipate storm behavior and assist in recognizing the hazards posed by severe thunderstorms. In supercells, fluctuations in low- and midlevel mesocyclone intensity along with the evolution of inflow and the rear-flank downdraft (RFD) provide signals for overall storm intensity and potential tornadogenesis. With the completion of the dual-polarization upgrade to the Weather Surveillance Radar 1988 Doppler (WSR-88D) network, new signatures such as midlevel Z_DR rings and low-level Z_DR arcs may provide additional cues to forecasters about a storm's intensity and tornadic potential.

A research dual-polarization WSR-88D located in Norman, Oklahoma (KOUN) performed 90° sector scans during several severe weather events during the spring and summer months of 2013. This specialized scanning provided rapid-scan (approximately 1.5-min volumetric updates) dual-polarization data of several tornadic and nontornadic supercells. The purpose of this study is to identify potential links and relationships between single-polarization features, such as mesocyclone intensity, and the previously identified dual-polarization supercell signatures such as Z_DR and ρ_hv rings, the K_DP foot, Z_DR and K_DP columns, Z_DR arcs, and the low-level inflow signature. Specifically, time series were produced of mesocyclone intensity and inflow magnitude depicted by Phased Array Radar and KOUN data, and then compared to time series of Z_DR ring magnitude at various elevation angles to show potential connections. Qualitative comparisons between single-polarization signatures (e.g., mesocyclone intensity; RFD evolution) and Z_DR rings and arcs, K_DP feet and columns, and ρ_hv rings and inflow signatures were also performed. The lead author will discuss key findings of this ongoing study.