Evaluating thunderstorm outflow boundaries in WRF-Fire

Thunderstorm outflow boundaries interact with wildland fires to cause rapid and severe changes in fire behavior, often threatening firefighter safety and causing economical destruction. Rapid spread and intensification of wildland fires have been linked to gust front interaction during the 2012 Colorado Waldo Canyon Fire (Johnson et al. 2014) and the 2013 Arizona Yarnell Hill Fire that killed 19 firefighters (Hardy and Comfort 2015; Paez et al. 2015).

Case studies have shown that these models, like the National Center for Atmospheric Research’s (NCAR) Weather and Research Forecasting model coupled with a wildland fire-behavior module (WRF-Fire), are now capable of predicting gust fronts and their interaction with the terrain and the fire as shown in Fig. 1 for the Arizona Yarnell Hill Fire. WRF-Fire has been used for numerous research case studies of large wildfires (Coen 2005; Coen and Riggan 2010).

The objectives of this project are to: (Obj. 1) Evaluate the ability of WRF-Fire in non-fire conditions to accurately predict the timing, location, and characteristics of thunderstorms and their outflow boundaries and their interactions with the local terrain by using state-of-the-art research instruments and operational networks; (Obj. 2) Evaluate forecast skills of WRF-Fire in terms of timing, location, and strength of thunderstorms and resulting outflow boundaries for past wildland fire events in complex terrain; and (Obj. 3) Develop and test ideas and approaches on how to evaluate forecast skills in real-time and how to best communicate outflow boundary characteristics and model uncertainties to the fire weather community. The research will synthesize state-of-the-art numerical modeling using WRF-Fire, currently used by the fire weather community, with operational as well as state-of-the art observational tools.