95 Single-Doppler Evidence of Supercell Vorticity Rivers

Tuesday, 23 October 2018
Stowe & Atrium rooms (Stoweflake Mountain Resort )
Erik Rasmussen, Cooperative Institute for Mesoscale Meteorological Studies, Norman, OK; and M. D. Flournoy, S. S. Murdzek, M. C. Mahalik, Z. B. Weinhoff, and H. Bluestein

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.

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