Kinematic Observations from the RiVorS Field Project

The Rivers of Vorticity in Supercells (RiVorS) field project took place in May-June 2017 across the U.S. Great Plains in an attempt to directly measure concentrated regions of enhanced vorticity that are present in many high-resolution numerical models. In these simulations, “vorticity rivers” emanated from the supercell’s main precipitation region, moved south- or westward toward the low-level updraft, and were associated with surface pressure deficits and cyclonic wind shifts. During RiVorS, mobile mesonet vehicles performed transects of these regions within supercells while mobile Doppler radar sampled the same storms from outside the precipitation. A diverse dataset from both tornadic and non-tornadic storms was collected.

Preliminary analysis of observed kinematic fields reveals the presence of a number of pronounced convergence zones. These features and their immediate surroundings are the focus of this study and are examined for their resemblance to modeled vorticity rivers. In addition, their relationships to storm structure, intensity, and tornado occurrence are explored through the use of quality-controlled mobile mesonet and radar data. Finally, the evolution of these features are compared to that of the parent storm as well as existing conceptual models, with a focus on the development of significant low-level rotation.