13.4 Undular bores, the low-level jet, convection initiation, and mesoscale convective systems over the Great Plains: overview of and early insights from the June-July 2015 PECAN campaign

Wednesday, 5 August 2015: 4:45 PM
Republic Ballroom AB (Sheraton Boston )
Bart Geerts, Univ. of Wyoming, Laramie, WY; and T. M. Weckwerth, D. Parsons, and C. Ziegler

A significant and sometimes dominant fraction of the warm-season precipitation falls at night in the central Great Plains in association with mesoscale convective systems (MCSs), at a time when values of surface-based Convective Available Potential Energy typically reach a diurnal minimum. During these nocturnal events, the lower troposphere in this region is characterized by a stable nocturnal boundary layer and a shallow southerly low level jet. Recent studies have shown that nocturnal MCSs often trigger undular bores and solitary waves within the stable boundary layer, yet their formation, diversity, evolution, and impact on convection initiation & MCS maintenance remain poorly understood. This talk will present the scientific rationale for a large, collaborative effort to explore these features, the recently completed PECAN (Plains Elevated Convection At Night) campaign. PECAN's overarching long-term goal is to improve understanding and prediction of continental nocturnal warm-season precipitation, through coordinated observations of the dynamics and microphysics of nocturnal MCSs, convection initiation, bores, as they interact with the stable boundary layer and the low-level jet. This talk will highlight some preliminary observations and findings emerging from the campaign.
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