An Unusual Line of Tornadic Supercells

The NSSL NOXP mobile Doppler radar observed a line of supercells on 12 June 2017 in Wyoming/Nebraska as part of the Rivers of Vorticity in Supercells (RiVorS) field program. RiVorS utilized two mobile mesonets NOXP, and sounding data collected from upsondes in the preexisting and near storm environment of severe convection to investigate and sample vorticity rivers in supercellular thunderstorms. The line of supercells was oriented approximately west-east with the newest member supercell on the east end, with the line moving to the northeast. However, movement of individual supercells was more complex with interactions occurring between all three supercells. All three supercells in the line were tornadic, including the westernmost member; more than 30 km behind a gust front emanating from the eastern member. In this presentation, high-resolution radar observations are used to show storm formation, structure, movement, and evolution that allowed for the unusual orientation. Mobile surface and upper air data from mobile research instruments and nearby conventional observations are used to help explain how rear, elevated, supercells were able to continue producing tornadoes for an extended period of time.