Evaluation of the Down-slope Wind Component in the High-Resolution Ensemble Forecast System for the Prediction of Large Wildfires

Abstract:

Local and mesoscale atmospheric conditions can greatly impact wildfire spread. Particularly, the combination of wind speed, wind direction, and local terrain features have the potential to further amplify these conditions. Accurately forecasting these localized conditions is important for the fire weather community, emergency managers, and the public. Using an ensemble of convection allowing models [CAMs; e.g., the High-Resolution Ensemble Forecast (HREF)], down-sloping winds can be forecast on a high-resolution grid (~3-km grid spacing). This presentation evaluates the effectiveness of the down-slope wind component in identifying dangerous fire-weather conditions. Down-slope wind forecasts from the HREF were examined for the largest wildfires from 2018 (e.g. Campfire, Carr, etc.). The HREF down-slope wind forecasts were evaluated against down-slope winds calculated from the real-time mesoscale analysis (RTMA) system to assess skill and reliability. Consideration of down-slope winds from CAM ensembles in the fire weather forecasting process may help improve short-term fire-weather outlooks.