Wednesday, 26 July 2017
Kona Coast Ballroom (Crowne Plaza San Diego)
During the Plains Elevated Convection at Night (PECAN) field campaign, 13 mesoscale convective system (MCS) environments were sampled by an array of instruments including over 500 radiosondes launched by three mobile sounding teams and a number of fixed and mobile PECAN integrated sounding array (PISA) sites. Vertical profiles of the observed pre-convective environments can generally be grouped into 3 categories: 1) those with a shallow inversion, an elevated low-level region of maximum 𝛉e and a largely unstable layer up to 500 mb; 2) those that maintain a daytime-like planetary boundary layer (PBL) and are moist neutral above the boundary layer; and 3) those that are moist neutral through the mid-levels and have a region of mid-level instability. Post-convective soundings demonstrate significantly more variability. Following convection, 𝛉 deficits range between approximately 1 and 11 K and over a depth of 150 m to over 4 km from case to case. Some post-convective soundings retain 1000 J/kg of convective available potential energy (CAPE) despite the passage of a convective line, while others have only minimal to a few hundred J/kg remaining CAPE. This work will examine the evolutions of the pre- and post-convective thermodynamic environments for a number of PECAN MCSs, and explore the relationships between these environments and the MCS organization and propagation.
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