The 6 May 2010 Elevated Supercell During VORTEX2

Abstract

n elevated supercell from VORTEX2 on 6 May 2010 is investigated. Observations show that the supercell formed over a stable inversion and was likely decoupled from the surface. Quintessential features of a supercell were present, including a hook echo (albeit bent anticyclonically) and mid-level mesocyclone, and the storm was quasi-steady during the observing period. A weak surface cold pool formed, but it was apparently devoid of air originating from mid-levels. Idealized modeling using near-storm soundings is used to clarify the structure and maintenance of this supercell. The simulated storm is decoupled from the surface by the stable layer. Additionally, the reflectivity structure of the simulated supercell is strikingly similar to the observed storm, including its peculiar anticyclonic-curving hook echo. Air parcels above 1 km reached their LFCs due to the simulated supercell's own dynamic lifting, which likely maintained the main updraft throughout its life. In contrast, low-level air in the simulation followed an ?up-down? trajectory, being lifted dynamically within the stable layer before becoming strongly negatively buoyant and descending back to the surface. Up-down parcels originating in the lowest 100 m are shown to be a potential driver of severe surface winds. The complementary observations and simulations highlight a range of processes that may act in concert to maintain supercells in environments lacking surface-based CAPE.