Rapidly Updating 3DVAR Analysis of Squall Line

Rapidly updating, dynamically-adaptive three-dimensional data assimilation (3DVAR) products are compared and contrasted to single-radar and multi-radar/multi-sensor severe weather guidance algorithms and data from the Warning Decision Support System-Integrated Information (WDSS-II). Since most studies comparing these products have focused on tornadic and hail storm related severe weather events, this study examines two non-tornadic squall line cases. The 3DVAR analysis, which primarily uses data from the national WSR-88D network and the North American Model analysis, was available in 1km horizontal resolution with a temporal resolution of five minutes. Products produced by the 3DVAR analysis include the 3D wind field and derivatives such as vorticity and updraft helicity, as well as a model-simulated reflectivity field. WDSS-II products include quality-controlled single-radar base data products (reflectivity, radial velodoty) and multi-radar/multi-sensor products such as Maximum Expected Size of Hail (MESH), 3D reflectivity, and maximum azimuthal shear in the 0-3km AGL and 3-6km AGL levels. One major difference between 3DVAR and WDSS-II that the 3DVAR analysis creates a full three-dimensional wind field, while the WDSS-II products use radar-based proxies to infer severe weather potential. This comparative study highlights the performance of the 3DVAR analysis on linear convection.