Observations of Tornadoes and Supercells with the Horus Fully Digital S-band Phased Array Radar from Spring 2024 Deployments

The Horus fully digital S-band phased array radar (PAR) collected novel observations of supercells and tornadoes during the Spring 2024 convective season. Designed, built, and located at the University of Oklahoma’s Advanced Radar Research Center (ARRC) with support from the NOAA National Severe Storms Laboratory (NSSL), Horus is the first-of-its-kind radar serving as a demonstrator to explore and understand potential benefits to the meteorological community. While other past and present PAR platforms – such as the SPY-1A, ATD, and SKYLER-I and SKYLER-II – have collected datasets of deep convection (including tornadoes), these radars use analog or subarray-digital beamformers, and none are built upon the latest, fully digital architecture. However, the flexibility offered by a fully digital beamformer (namely element level control with improvements in digital beamforming capabilities) has yet to be evaluated using real-world datasets/observations. Thus, understanding how to best leverage the radar’s unique capabilities while optimizing trade-offs between data quality and temporal resolution remain open questions.

Data were collected with Horus on 27 April 2024 and 6 May 2024, including observations of at least 3–5 discrete or embedded supercells using digital beamforming techniques (e.g., 1D and 2D imaging scans). Comparisons of both supercell modes and their associated tornadic signatures (e.g., TVS, TDS, ZDR arc) will be presented using WSR-88D (e.g., KTLX) and Horus data to assess data quality differences and evaluate the benefits of higher temporal resolution that can potentially be achieved with adaptive scanning. Comparisons with WSR-88Ds at farther distances (e.g., KINX) will be presented as well to analyze observations with similar spatial resolution and any associated impacts (i.e., beam broadening) given the larger beamwidth of Horus to traditional mobile platforms. With supercells that undergo rapid cyclic mesocyclogenesis or merge with or into a QLCS-type structure, such as the 27 April 2024 Norman, OK, supercell, Horus provides invaluable data for identifying tornado precursors, tornadic vortices, or tornadic debris signatures from short-lived tornadoes that may have occurred at time scales shorter than the volume scan times the WSR-88D can offer. The potential utility of observations by platforms like Horus likely includes earlier detection of deviant motion and storm splitting with improved observations of rapidly evolving convective dynamics. Thus, evaluating the data collected by Horus – especially the novel 2D imaging data of tornadoes and mesocyclones – represents a crucial step in understanding its potential meteorological benefits and its performance through analysis of its observations at temporal scales previously unavailable beyond X-band and C-band mobile platforms.