Turbulence in MCS anvils: observations and analyses from BAMEX

The occurrence of large mesoscale convective systems (MCSs) during the warm season over much of the central United States presents a hazard to aviation that has not been thoroughly assessed. In addition to lightning and hail, the extensive mid- to upper-level anvil clouds that form in these systems can cause severe turbulence. Although avoidance of the most intense convection by passenger aircraft and general aviation is usually possible, it is advantageous to know the risk of turbulence in regions within and close to the anvil clouds, especially during latter stages of development when anvil features are not as clearly delineated. With sufficient risk determination, aircraft travel through these large anvils could become acceptable. Furthermore, if an algorithmic estimate of this risk could be developed, it could contribute to turbulence forecasting and warning. We examine the composite structure of an MCS which occurred on 10 June 2003 during the Bow Echo and Mesoscale Vortex Experiment (BAMEX) using observations made by three research aircraft, including dropsondes launched from inside the anvil, standard 1 Hz and 40 Hz meteorological flight-level aircraft data, and RUC model analyses. Quantitative identification of turbulence regions was made by intercomparison of aircraft accelerometer records, scientist logs and nearby dropsonde observations. Our results suggest the feasibility and potential value of these analyses for development of schemes leading to improved forecasts of turbulence near and within upper- and mid-tropospheric MCS anvils.