Characteristics of Low-Reflectivity Ribbons in Simulated Supercells

The increased use of high-resolution mobile radars to observe supercell thunderstorms in recent years has led to the discovery of new and unexplained phenomena within these storms not possible with traditional, fixed-site radar systems. One such phenomenon is the low-reflectivity ribbon, a narrow band characterized by a deficit in reflectivity bisecting the forward- and rear-flanks of some supercells. Low-reflectivity ribbons have been identified in at least seven supercells since 2008 (Snyder et al. 2012). Characteristics of low-reflectivity ribbons identified thus far include cyclonically rearward movement around the low-level mesocyclone, positive vertical vorticity, and an overlying updraft (Kosiba et al. 2013, Snyder et al. 2013, Griffin 2015). Additionally, low-reflectivity ribbons are often quite narrow, with widths ranging from 300 – 1000 m (Griffin 2015). Since low-reflectivity ribbons are rather new to the published literature, their importance is still unknown, and it is unclear whether they have any relevance to tornadogenesis or just a feature common in supercells when observed with high-resolution radar.

Several low-reflectivity ribbons have been identified in an ensemble of thirty supercells simulations based on the nontornadic and tornadic composite environments from the second Verification of the Origins of Rotation Experiment (VORTEX2). Characteristics of these features will be documented to show their thermodynamic and kinematic structures in detail not possible with observations.