551 Frontogenesis Three main frontogenetical areas in a typical developing cyclone • Deformation frontogenesis with cold front • Deformation (confluence)frontogenesis with warm front • Convergence frontogenesis near low center (generally on portion of warm front closest to the low center) Using Garp software Numerical Simulation of the Dec. 14-16, 1987 event • Mass and Shultz, 1993 • Shultz and Mass, 1993 • Monthly Weather Review Note fracture in frontogenesis along northern portion of CF Important issue we will discuss in depth: Frontogenesis generally accompanies cyclogenesis Surface-based fronts typically weaken with height How do we explain this? Classic Paper That First Applied Frontogenesis Diagnosis 3D for a real case: Sanders 1955 Surface-based Fronts Weakening With Height • Rising motion and adiabatic cooling on warm side. • Sinking and adiabatic warming on on cold side. • Vertical motions increase with height…therefore vertical motions increasingly work against frontogenesis with height.