Observations of the 9 June 2009 Dissipating Supercell from VORTEX2

Abstract

n 9 June 2009, the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) captured a unique dataset of dense observations throughout the lifetime of an isolated supercell, including its demise. This event provides a rare opportunity to explore the conditions and processes associated with supercell demise, as well as add to our understanding of supercell maintenance within the context of storm?environment interactions. The target storm on 9 June formed just to the cool side of a quasi-stationary boundary and initially exhibited strong low-level rotation. Over time, however, the storm moved deeper into the cool air and completely dissipated. Three near-inflow soundings launched over the lifetime of the supercell illustrated an increase in low-level convective inhibition (CIN) over time. However, an elevated layer containing sufficient instability and modest inhibition was also present, suggesting an unrealized potential for elevated convection. The near-storm environment also demonstrated a notable decrease in bulk vertical wind shear and storm-relative helicity over the lifetime of the storm. Although the likely impact of an increasingly stable near-storm environment is seemingly straightforward, the extent to which the evolving wind profile influenced storm dissipation is less certain. Dual-Doppler wind syntheses suggest decreases in the production of updraft vertical vorticity via tilting and stretching, indicating that the storm demise may have resulted from a complicated interplay between stabilization and changing environmental shear.