A convection initiation case study during COPS: 6 August 2007

The Convective and Orographically-induced Precipitation Study (COPS) was conducted during the summer of 2007 in southwestern Germany and eastern France. The COPS region included the Vosges Mountains of France, the Rhine Valley which straddles France and Germany, the Black Forest Mountains of Germany and the Swabian Mountains of Germany. COPS was aimed at advancing the quality of forecasts of orographically-induced convective precipitation with the use of 4-D observations and modeling of its life cycle. One of the components of improving quantitative precipitation forecasting skill is better understanding of convection initiation processes.

On 6 August 2007 a frontal system approached the COPS low-mountain region from the west. In advance of the front, convection initiated along the Vosges Mountains. The storms propagated eastward into the Rhine Valley and produced an outflow boundary that supported secondary initiation.

Dual-Doppler observations were obtained from the Doppler on Wheels (DOW) mobile radars. These systems provided clear-air measurements prior to convection forming in the Vosges Mountains, as well as information about the evolution of the system during its propagation across the Rhine Valley. Additional information about the pre-convective environment will be assessed with the use of surface stations, soundings and GPS moisture retrievals. Comparisons of the observations with high-resolution WRF (Weather Research and Forecasting) simulations will be shown to highlight the necessary features for convective development on this day.