Performance diagrams with σ = 50 corresponding to differing updraft helicity (UH) thresholds: (a) 25, (b) 75, and (c) 125 m2 s−2. Colored curves represent the POD plotted vs the success ratio (1-FAR) at all probability levels forecasted, and the colored dot highlights 15% probability. Dashed lines are of constant bias, and curved lines are of constant critical success index (CSI). Probability methods include UH only (black), LCL < 1500 m and surface-based CAPE/most unstable CAPE (SBCAPE/MUCAPE) > 0.75 (blue), significant tornado parameter (STP) ≥ 1 (green), and LCL < 1500 m, SBCAPE/MUCAPE > 0.75, and STP ≥ 1 (red).
Citation: Weather and Forecasting 31, 4; 10.1175/WAF-D-16-0076.1