12B.2 Kinematics, Thermodynamics, and Microphysics of the 25-26 June 2015 Kansas MCS during PECAN

Thursday, 26 January 2017: 8:45 AM
Conference Center: Tahoma 3 (Washington State Convention Center )
Rachel L. Miller, CIMMS, Norman, OK; and C. L. Ziegler and M. I. Biggerstaff

This study analyzes a nocturnal mesoscale convective system (MCS) that was observed in northeast Kansas by the Plains Elevated Convection At Night (PECAN) field project on 25-26 June 2015. Over the course of the observational period, a broken line of nocturnal convective cells initiated around 0230 UTC on the cool side of a surface cold front and subsequently merged into a quasi-linear MCS that later matured and developed strong outflow and a trailing stratiform region. The present analysis will synthesize observations from up to 6 mobile radars, as well as mobile mesonets, mobile and fixed soundings, AERI and Doppler wind lidar profiles, and aircraft measurements.  These observations will be combined to create multiple time-spaced wind syntheses, which in turn will be assimilated into a diabatic Lagrangian analysis (DLA) to derive information about the thermodynamic, cloud, and precipitation structure of the MCS.

One of the main goals of PECAN is to determine whether nocturnal MCSs are elevated or surface-based and how the stable nocturnal boundary layer influences the MCS structure, evolution, and movement. A sample 4-radar analysis of the 26 June MCS at 0500 UTC (see attached image) reveals an inferred surface-based cold pool with air ascending from the surface into the updraft to form a front-to-rear (FTR) flow and a corresponding rear-to-front (RTF) flow that descends toward the surface behind and through the main reflectivity cores. Calculated Lagrangian trajectories from time-series wind analyses will reveal the source layers of air parcels (surface or elevated), allow us to determine the evolution of source levels as the MCS develops from the initial convective line to the mature MCS stage, and how radar properties of air parcels change while traversing the different sections of the MCS. Combining these 3-D airflow analyses with DLA, we will additionally infer the altitude and thermodynamic origins of updraft, downdraft, and mesoscale cold pool parcels, assess the diabatic thermodynamic forcing along selected air trajectories, derive the mesoscale cold pool depth and structure, and determine whether the MCS updrafts, downdrafts, and cold pool are elevated or surface-based.

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