From 'Assessing Crown Fire Hazard': 'Scott and Reinhardt (in preparation) developed two quantitative indices of crown fire hazard--the Torching Index and the Crowning Index --that managers can use to assess the potential for crowing by wildfires. The indices are derived from links among separate models. The Torching Index is the 20-foot (6-m) windspeed at which a crown fire could start. The Crowning Index is the 20-foot (6-m) windspeed at which an active crown fire is possible. Scott and Reinhardt also showed how the crown fire modeling concepts used in the Canadian Forest Fire Behavior Prediction System (Forestry Canada Fire Danger Group 1992) can be applied to the fire behavior models used in the United States. To implement their coupled model of surface and crown fire behavior, Scott and Reinhardt developed an Excel-based spreadsheet application, called NEXUS, that couples Rothermel's (1972) surface fire and (1991) crown fire models to simulate the full range of fire behavior possible in a forest stand.'