TORUS 2019 Highlights from the TTUKa Mobile Doppler Radars

The ongoing Targeted Observation by Radars and UAS of Supercells (TORUS) project seeks to characterize the structure of storm-scale boundaries generated by supercell thunderstorms, in an effort to better understand how they facilitate or obstruct the development of low-level vertical vorticity. During the first of two field phases in spring 2019, an armada of surface and airborne instrumentation, including three ground-based radars, three unmanned aircraft, the NOAA P-3, and sounding and profiling platforms, coordinated to gather observations on a number of supercells across the Plains.

This presentation will relay the highlights from data collected by the two TTUKa mobile Doppler radars. Over the 16 active field operations days, the TTUKa radars intercepted 19 separate storms (eight of them tornadic), with a total of 67 deployments over the span. Range-height indicator (RHI) scans were prioritized for most of these deployments to help achieve a number of objectives tied to the vertical structure of various storm-scale boundaries.

Foremost among the research goals is validation of streamwise vorticity currents, channels of strong streamwise vorticity revealed by recent high-resolution numerical modeling studies (e.g., Orf et al. 2017; Schueth and Weiss 2019) to reside within the left/forward flank of some supercells, sourcing strong vertical vorticity in the updraft through tilting and three-dimensional stretching. As this feature can be rather compact, and has been shown to often reside in the lowest few hundred m AGL, the narrow half-power beamwidth of the Ka-band radars was useful in interrogating a wide swath of the left/forward flank of target storms in search of this feature. Preliminary results from this objective and others tied to gust front slope/buoyancy deficit association, RFD surges and vertical vorticity maxima within the left flank will be presented.