Single-Doppler Evidence of Supercell Vorticity Rivers

Recent numerical simulations have revealed the possible importance of a “river of vorticity” in potentially tornadic supercell thunderstorms. This is a current of near-ground air emanating from the forward/left flank precipitation region. It can be rich in streamwise horizontal vorticity which, upon tilting, can produce vertical vorticity near the ground. Then, depending on low-level stretching, this vertical vorticity can be intensified toward tornadic strength.

This study examines single-Doppler data for evidence of supercell vorticity rivers. Single-Doppler signatures should be expected based on the kinematic features present in the numerical simulations. In particular, the vertical shear of the radial velocity is used as a proxy for horizontal vorticity, and its three-dimensional structure is examined. The presence and strength of various signatures will be used to evaluate the realism of the numerical simulations.