Cold pool forcing of the 9 June 2009 Greensburg, KS supercell during VORTEX2

This study documents the late evolution of the cold pool of the 9-10 June 2009 Greensburg, KS, supercell using VORTEX2 observations and a newly developed diabatic Lagrangian analysis technique. The Lagrangian analysis first calculates backward air trajectories from analysis gridpoints into the storm environment. After initializing each back-trajectory using an environmental sounding, the Lagrangian analysis then calculates time-dependent microphysical moistening-evaporation and diabatic heating-cooling changes in the forward trajectory direction to obtain the 3-D fields of potential temperature, water vapor mixing ratio, and cloud liquid content at any given analysis time. Rain and graupel contents for calculating evaporation, melting, and other microphysical tendencies are estimated from radar reflectivity.

Observations and Lagrangian cold pool analysis commence prior to the development of an intense low-level mesocyclone and proceed through the storm's decay phase (~ 2345-0024 UTC). A series of wind syntheses incorporate up to 5 Doppler radars (SR1, SR2, NOXP, and DOW6 mobile radars and the Dodge City WSR-88D), and estimate the smoothed storm-environmental mesoscale wind field employing mobile environmental soundings. These augmented radar-sounding wind analyses provide a storm-scale context to force the Lagrangian analysis, while both the wind syntheses and the Lagrangian analyses provide context to interpret in-situ observations from mobile mesonets and Sticknets. The storm was observed to move into colder BL air and a more stable environment as it peaked in overall intensity, before subsequently decaying as an LP storm.

We will examine the evolution of the Greensburg storm's Lagrangian-analyzed 3-D cold pool structure in relation to the overall storm evolution. The Lagrangian air trajectories will help define the thermodynamic evolution along trajectories that fed the forward- and rear flank downdrafts, the low-level mesocyclone, and the main updraft with respect to the early supercell structure and the storm's subsequent decay as it moved into an increasingly stable environment.