Comparison of Canadian Forest Fire Danger Rating System and National Fire Danger Rating System fire indices derived from Weather Research and Forecasting (WRF) model data for the June 2005 Interior Alaska wildfires

Standard indices of the National Fire Danger Rating System (NFDRS) and Canadian Forest Fire Danger Rating System (CFFDRS) are calculated from Weather Research and Forecasting (WRF) model forecasts and observations in Interior Alaska for June 2005. Fire indices determined from WRF results of all forecast-leads and the ensemble do not differ statistically significantly from those calculated from observations. WRF-derived CFFDRS and NFDRS fire indices capture the temporal evolution of fire indices calculated from observations acceptably. Sensitivity to errors in meteorological forecasts differs for the various fire indices. Failure to predict a peak does not necessarily occur at the same time for the various indices within and/or among the two systems. Predicted buildup-index and spread component capture trends, the time of peaks and minima most reliably. Overall for the CFFDRS the lowest relative errors exist for fine fuel moisture content followed by buildup-index while for the NFDRS the lowest relative errors occur for energy release component followed by burning index. When fire indices are calculated from meteorological forecasts predicting fire risk and identifying the right site becomes more difficult as fire risk increases. Fire risk forecast skill depends on meteorological forecast-lead slightly for energy release rate and ignition component and notably for all CFFDRS-indices except fine fuel moisture content.